Wikipedia project page
This page guides the presentation of numbers, dates, times, measurements, currencies, coordinates, and similar items in articles. The aim is to promote clarity, cohesion, and consistency, and to make the encyclopedia easier and more intuitive to use. For numbers, dates, and similar items in Wikipedia article titles, see the
"Naming conventions (numbers and dates)"
guideline.
Where this manual gives options, maintain consistency within an article unless there is a good reason to do otherwise. The
Arbitration Committee
has ruled that editors should not change an article from one guideline-defined style to another without a substantial reason unrelated to mere choice of style;
edit-warring
over optional styles is unacceptable.
[a]
If discussion fails to resolve the question of which style to use in an article, defer to the style used by the first major contributor.
Quotations, titles, etc.
[
edit
]
Quotations, titles of books and articles, and similar "imported" text should be faithfully reproduced, even if they use formats or units inconsistent with these guidelines or with other formats in the same article. If necessary, clarify via [bracketed interpolation], article text, or footnotes.
Non-breaking spaces
[
edit
]
Guidance on the use of
non-breaking spaces
("hard spaces") is given in some sections below, but not all situations in which hard spaces (
{{
nbsp
}}
or
) or
{{
nowrap
}}
may be appropriate are described.
For further information see
Wikipedia:Manual of Style §?Non-breaking spaces
and
Wikipedia:Line-break handling
.
Statements likely to become outdated
[
edit
]
Except on pages that are inherently time-sensitive and updated regularly (e.g.
the "Current events" portal
), terms such as
now
,
today
,
currently
,
present
,
to date
,
so far
,
soon
,
upcoming
,
ongoing
, and
recently
should usually be avoided in favor of phrases such as
during the 2010s
,
since 2010
, and
in August 2020
. Wording can usually be modified to remove the "now" perspective: not
she is the current director
but
she became director on 1 January 2024
; not
2010?present
but
beginning in 2010
or
since 2010
. Terms likely to go out of date include
best known for
,
holds the record for
, etc.
[b]
For current and future events, use phrases such as
as of June 2024
or
since the beginning of 2024
to signal the time-dependence of the information; use the template
{{
as of
}}
(or
{{
updated
}}
) in conjunction.
Relative-time expressions are acceptable for very long periods, such as geological epochs:
Humans diverged from other primates long ago, but
only recently developed state legislatures
.
Dates, months, and years
[
edit
]
"WP:YEAR" redirects here. For WikiProject Years, see
WP:YEARS
.
Formats
[
edit
]
Acceptable date formats
General use
|
Only in limited situations
where brevity is helpful
[c]
|
Comments
|
2
September 2001
|
2
Sep 2001
|
A comma doesn't follow the year unless otherwise required by context:
- The 5 May 1922 meeting was cancelled.
- Except Jones, who left London on 5 March 1847, every delegate attended the signing.
|
September
2, 2001
|
Sep
2, 2001
|
A comma follows the year unless
other punctuation obviates it
:
- The weather on March 12, 2005, was clear and warm.
- Everyone remembers July
20, 1969?? when humans first landed on the Moon.
|
2
September
|
2
Sep
|
Omit year only where there is no risk of ambiguity:
- The 2012 London Olympics ran from 25
July to 12
September.
- January
1 is New Year's Day.
|
September
2
|
Sep
2
|
No equivalent for
general use
|
2001-09-02
|
Use
yyyy
-
mm
-
dd
format only with
Gregorian
dates from 1583 onward.
[d]
|
September 2001
|
Sep 2001
|
|
- Dates, years, and other chronological items should be linked only when they are relevant to the subject
and
likely to be useful to a reader; this rule does not apply to articles that are explicitly on a chronological item, e.g.
2002
,
19th century
(as discussed at
Wikipedia:Linking §?Chronological items
)
.
[e]
- For issues related to dates in sortable tables,
see
Help:Sortable tables §?Configuring the sorting
and
Help:Sortable tables §?Date sorting problems
, or consider using
{{
dts
|Nov 1, 2008}}
.
- Phrases such as
Fourth of July
(or
July
Fourth
, but not
July
4th
),
Cinco de Mayo
,
Seventh of March Speech
, and
Sete de Setembro
are proper names, to which rules for dates do not apply (
A typical Fourth of July celebration includes fireworks
).
Unacceptable date formats (except in
external titles and quotes
)
Unacceptable
|
Corrected
|
Comments
|
Sep
.
2
|
Sep 2
[c]
|
Do not add a full stop (period) to an abbreviated month or to the
day-of-month
.
[f]
|
9
.
June
|
9
June
or
June
9
|
9 june
june 9
|
Months should be capitalized.
|
9th June
June 9th
the 9th of June
|
Do not use
ordinals
(
1st
,
2nd
,
3rd
, etc.).
|
09-06
06-09
|
Do not use these formats.
|
09 June
June 09
|
Do not zero-pad day
...
|
2007-4-15
|
2007-04-15
[c]
|
... except in all-numeric
(
yyyy
-
mm
-
dd
) format
, where both month and day should be zero-padded to two
digits.
|
2007/04/15
|
Do not use separators other than hyphens.
|
20070415
|
Do not omit the hyphens.
|
07-04-15
|
Do not abbreviate year to two digits.
|
15-04-2007
04-15-2007
2007-15-04
|
Do not use
dd
-
mm
-
yyyy
,
mm
-
dd
-
yyyy
or
yyyy
-
dd
-
mm
formats.
[g]
|
2007 April 15
2007 Apr 15
|
Do not use these formats.
|
7/2001
7-2001
07-2001
2001-07
2001 July
July of 2001
|
July 2001
|
Do not use these
formats.
|
July
,
2001
|
No comma between month and
year.
|
3 July
,
2001
|
3
July 2001
|
July 3 2001
|
July
3
,
2001
|
Comma required between day and
year.
|
the
'
97 elections
the
97 elections
|
the 1997 elections
|
Do not abbreviate year.
|
Copyright MMII
|
Copyright 2002
|
Roman numerals
are not normally used for
dates.
|
Two thousand one
|
2001
|
Years and days of the month are not normally written in
words.
|
the first of May
May the first
|
1
May
or
May
1
|
June 0622
|
June 622
|
Do not zero-pad years.
|
June 2
,
015
|
June 2015
|
Do not add a comma to a four-digit year.
|
sold in the year 1995
|
sold in 1995
|
Write "the year" only where needed for clarity (
About 200 ships
arrived in
the year 300
).
|
Consistency
[
edit
]
- Dates in article body text
[h]
should all use the same format:
She fell ill on
25 June 2005
and died on
28 June
, not
She fell ill on
25 June 2005
and died on
June 28
.
- Publication dates
in an article's citations should all use the same format, which may be:
- the format used in the article body text,
- an abbreviated format from the
"Acceptable date formats" table
, provided the day and month elements are in the same order as in dates in the article body
- the format expected in the
citation style
being used (but all-numeric date formats other than
yyyy
-
mm
-
dd
must still be avoided).
For example, publication dates within a single article might be in one, but only one, of these formats (among others):
- Jones, J. (20 September 2008)
- Jones, J. (September 20, 2008)
If an article uses a template such as
{{
Use mdy dates
}}
or
{{
Use dmy dates
}}
, then
Citation Style 1
and
2
templates automatically render dates (
|date=
,
|access-date=
,
|archive-date=
, etc) in the specified format, regardless of the format they are entered in. (The
|cs1-dates=
parameter can be used to fine-tune the generated output,
see
Template:Use mdy dates §?Auto-formatting citation template dates
.)
- Access and archive dates
in an article's citations should all use the same format, which may be:
- the format used for publication dates in the article (see above);
- the format expected in the citation style adopted in the article; or
- yyyy
-
mm
-
dd
For example, access/archive dates within a single article might be in one, but only one, of these formats (among others):
- Jones, J. (September 20, 2008)
... Retrieved February 5, 2009.
- Jones, J. (20 Sep 2008)
... Retrieved 5 Feb 2009.
- Jones, J. (20 September 2008)
... Retrieved 2009-02-05.
When a citation style does not expect differing date formats, it is permissible to normalize publication dates to the article body text date format, and/or access/archive dates to either, with date consistency being preferred.
Strong national ties to a topic
[
edit
]
For any given article, the choice of date format and the choice of national variety of English (see
Wikipedia:Manual of Style §?Strong national ties to a topic
) are independent issues.
- Articles on topics with strong ties to a particular English-speaking country should generally use the date format most commonly used in that nation. For the United States this is (for example)
July 4, 1976
; for most other English-speaking countries it is
4 July 1976
.
- Articles related to Canada may use either format with (as always) consistency within each article. (
see Retaining existing format
)
In topics where a date format that differs from the usual national one is in customary usage, that format should be used for related articles: for example, articles on the modern US military, including biographical articles related to the modern US military, should use day-before-month, in accordance with US military usage.
Retaining existing format
[
edit
]
- If an article has evolved using predominantly one date format, this format should be used throughout the article, unless there are reasons for changing it based on strong national ties to the topic or consensus on the article's talk page.
- The date format chosen in the first major contribution in the early stages of an article (i.e., the first non-stub version) should continue to be used, unless there is reason to change it based on strong national ties to the topic or consensus on the article's talk page.
- Where an article has shown no clear sign of which format is used, the first person to insert a date is equivalent to "the first major contributor".
Era style
[
edit
]
- The default
calendar eras
are
Anno Domini
(
BC
and
AD
) and
Common Era
(
BCE
and
CE
). Either convention may be appropriate for use in Wikipedia articles depending on the article context. Apply
Wikipedia:Manual of Style §?Retaining existing styles
with regard to changes from one era to the other.
- Use either the BC?AD or the BCE?CE notation consistently within the same article. Exception: do not change
direct quotations
, titles, etc.
- An article's established era style should not be changed without reasons specific to its content; seek consensus on the talk page first (applying
Wikipedia:Manual of Style §?Retaining existing styles
) by opening a discussion under a heading using the word
era
, or another similarly expressive heading, and briefly stating why the style should be changed.
- BCE and CE or BC and AD are written in upper case, unspaced, without a full stop (period), and separated from the numeric year by a space (
5
BC
, not
5BC
). It is advisable to use a
non-breaking space
.
- AD appears before or after a year (
AD
106
,
106
AD
); the other abbreviations appear only after (
106
CE
,
3700
BCE
,
3700
BC
).
- In general, omit CE or AD, except to avoid ambiguity or awkwardness.
- Typically, write
The
Norman Conquest
took place in 1066
not
1066
CE
or
AD
1066
.
- But
Plotinus
lived at the end of the 3rd century AD
(not simply
at the end of the 3rd century
) may avoid confusion unless the era is clear from context.
- One- and two-digit years may look more natural with an era marker (
born in 2
AD
or
born January 15, 22
CE
, not
born in 2
nor
January 15, 22
).
- Ranges beginning in BC/BCE should specify the ending era: write
450 to 200 BCE
or
450 BC to 200 BC
or
450 BCE to 200 CE
, but not
450 BCE to 200
. (
see
Ranges
)
- Uncalibrated (BCE) radiocarbon dates:
Calibrated and uncalibrated
dates can diverge widely, and some sources distinguish the two only via BCE or BC (for calibrated dates) versus bce or bc (uncalibrated). When feasible, avoid uncalibrated dates except in direct quotations, and even then ideally give the calibrated date in a footnote or square-bracketed note??
[3250?BCE calibrated]
, or at least indicate the date type??
[uncalibrated]
. This also applies to other dating systems in which a calibration distinction is drawn.
- BP or YBP
: In scientific and academic contexts, BP (Before Present) or YBP (years Before Present) are often used. (
Present
in this context by convention refers to January
1, 1950.) Write
3000 years
BP
or
3000
YBP
or
3000
years before present
but not forms such as
3000 before present
and
3000 years before the present
. If one of the abbreviated forms is used, link to
Before Present
on first use:
The Jones artifact was dated to 4000
YBP
, the Smith artifact to 5000 YBP.
- Other era systems
may be appropriate in an article. In such cases, dates should be followed by a conversion to Anno Domini or Common Era, and the first instance linked:
Qasr-al-Khalifa was built in
221
AH
(836
CE)
, or
in 836
AD (221
AH
)
.
- Astronomical year numbering
is similar to the Common Era. There is no need to follow a year expressed with astronomical year numbering with a conversion to Common Era. The first instance of a non-positive year should still be linked:
The March equinox passed into Pisces in
year
?67
.
(The expressions
?67
and
68 BCE
refer to the same year.)
Julian and Gregorian calendars
[
edit
]
A date can be given in any appropriate calendar, as long as it is (at the minimum) given in the
Julian calendar
or the
Gregorian calendar
or both, as described below. For example, an article on the early
history of Islam
may give dates in both
Islamic
and Julian calendars. Where a calendar other than the Julian or Gregorian is used, the article must make this clear.
- Current events are dated using the Gregorian calendar.
- Dates of events in countries using the Gregorian calendar at that time are given in the Gregorian calendar. This includes some of the
Continent of Europe from 1582
, the
British Empire
from 14
September 1752, and Russia from 14
February 1918
(see
Adoption of the Gregorian calendar
)
.
- Dates before 15
October 1582 (when the Gregorian calendar was first adopted in some places) are normally given in the Julian calendar.
- Dates after 4
October
1582 in a place where the Julian calendar was observed should be given in the Julian calendar.
- For either the Julian or Gregorian calendars, the beginning of the year should be treated as 1
January even if a different start-of-year date was observed in the place being discussed.
- Dates for Roman history before 45
BC are given in the
Roman calendar
, which was neither Julian nor Gregorian. When (rarely) the Julian equivalent is certain, it may be included.
- For dates in early Egyptian and Mesopotamian history, Julian or Gregorian equivalents are often uncertain. Follow the consensus of reliable sources, or indicate their divergence.
The dating method used should follow that used by reliable secondary sources (or if reliable sources disagree, that used most commonly, with an explanatory
footnote
). The guidance above is in line with the usage of reliable sources such as
American National Biography
,
[1]
Oxford Dictionary of National Biography
, and
Encyclopædia Britannica
.
[i]
Where it is not obvious that a given date should be given in Julian alone or in Gregorian alone, consider giving both styles, for example by using
{{
OldStyleDate
}}
. If a date appears without being specified as Old Style or New Style, tagging that date with
{{
which calendar?
}}
will add the page to
Category:Articles containing ambiguous dates
for further attention.
If an article contains Julian calendar dates after 4 October 1582 (as in the
October Revolution
), or if a start-of-year date other than 1 January was in force in the place being discussed, or both, a footnote should be provided on the first usage, explaining the calendar usage adopted for the article. The calendar usage should be compatible with this guideline.
Ranges
[
edit
]
- A simple
year?year
range is written using an
en dash
(
?
,
–
or
{{
ndash
}}
, or
{{
nbnd
}}
for a non-breaking en dash), not an em dash, hyphen, or slash; this dash is
unspaced
(that is, with no space on either side); and the end year is usually given in full:
- 1881?1882
;
1881?1886
(not
1881?86
);
1881?1892
(not
1881?92
)
- Markup:
1881
{{
ndash
}}
1882
or
1881–1882
- Although non-abbreviated years are generally
preferred
,
two-digit ending years
(
1881?82
, but never
1881?882
or
1881?2
)
may
be used in any of the following cases: (1) two consecutive years; (2)
infoboxes
and tables where space is limited (using a single format consistently in any given table column); and (3) in certain topic areas if there is a very good reason, such as matching the established convention of reliable sources.
[j]
For consistency, avoid abbreviated year ranges when they would be used alongside non-abbreviated ranges within an article (or related pages, if in titles). Never use abbreviated years for ranges across centuries (
1999?2000
, not
1999?00
) or for years from the first millennium (
886?887
, not
886?87
).
- The
slash notation
(
2005/2006
) may be used to signify a fiscal year or other special period, if that convention is used in reliable sources.
- Other "simple" ranges use an
unspaced
en dash as well:
- day?day
:
5?7
January 1979
;
January
5?7, 1979
;
elections were held March 5?8
.
- month?month
:
the 1940 peak period was May?July
;
the peak period was May?July
1940
;
(but
the peak period was
May 1940?? July
1940
uses a
spaced
en dash;
see below
)
- In certain cases where at least one item on either side of the en dash contains a space, then a
spaced
en dash (
{{
snd
}}
) is used. For example:
- between specific dates in different months
:
They travelled
June
3?? August
18,
1952
;
They travelled 3
June?? 18
August 1952
- between dates in different years
:
- Charles Robert Darwin
(12
February
1809?? 19
April
1882) was an English naturalist
...
- Markup:
12
{{
nbsp
}}
February 1809
{{
snd
}}
19
{{
nbsp
}}
April 1882
or
12 February 1809 – 19 April 1882
- Abraham Lincoln
(February
12, 1809?? April
15, 1865) was the 16th president of
...
- between months in different years
:
The exception was in force August
1892?? January
1903
;
The Ghent Incursion (March 1822?? January
1, 1823) was ended by the New Year's Treaty
- Markup:
March 1822
{{
snd
}}
January
{{
nbsp
}}
1, 1823
or
March 1822 – January 1, 1823
- Where
era designations
,
c.
or
other modifiers
are present (
see
§?Uncertain, incomplete, or approximate dates
):
- if the modifier
applies to only one of the two endpoints of the range
, use a
spaced
en dash:
150 BCE?? 50 BCE
,
5 BC?? 12 AD
,
c. 1393?? 1414
- if the modifier
applies to the range as a whole
,
disregard
the modifier:
150?50 BCE
,
reigned 150 BCE?? 50 BCE
,
reigned 150?50 BCE
,
r.
c.
?1393
???1414
,
r.?1393?1414
.
- Use an en dash, or a word such as
from
or
between
, but not both:
from 1881 to 1886
(not
from 1881?1886
);
between June
1 and July
3
(not
between June
1?? July
3
)
- MOS:DATED
says "terms such as ... 'present' should usually be avoided". For ranges, if
"to present"
or
"?present"
is used, the current year (or, in cases where necessary, date) of "present" at the time of writing should be included. Thus
1982?present (as of 2024)
?? if writing in 2024?? is preferable to
1982?present
. If the "from" date has an internal space, a spaced en dash is used. Other constructions may be more appropriate in prose
(see
§?Statements likely to become outdated
)
. An alternative form is
Since 1982
.
- In tables and infoboxes where space is limited,
pres.
may be used (
1982?pres.
). Do not use incomplete-looking constructions such as
1982?
and
1982?...
.
- Consider adding the
{{
As of
}}
, or
{{
Update after
}}
templates to such constructions, depending on how important it is for editors to keep "present" up to date.
For a
person still living
:
Serena Williams
(born September
26, 1981) is a
...
, not
(September
26, 1981?? )
or
(born on September
26, 1981)
.
Do not use
*
to indicate
born
; use
b.
only where space is limited e.g. tables and infoboxes; use either
born
or
b.
consistently in any given table column.
Where
birthdate is unknown
:
John Smith
(died May
1, 1622)
or
John Smith
(died 1622)
Do not use
†
to indicate
died
; use
d.
only where space is limited, with consistency within any given table column.
An
overnight period
may be expressed using a slash between two contiguous dates:
the night raids of 30/31
May 1942
or
raids of 31
May
/ 1
June 1942
.
Or use an en dash: (unspaced)
raids of 30?31
May 1942
;
(spaced)
raids of
31
May?? 1
June
1942
.
- The
{{
Age
}}
template can keep ages current in infoboxes and so on:
{{age|1989|7|23}}
returns:
34
{{age|1989|7|23}}-year-old
returns:
34-year-old
{{age|1989|7|23}} years old
returns:
34 years old
- Date mathematics templates
are available for other age calculations.
Uncertain, incomplete, or approximate dates
[
edit
]
- To indicate "around", "approximately", or "about", the use of the
{{
circa
}}
template is preferred at first occurrence over just
c.
. At later occurrences,
c.
is preferred over
circa
,
c
,
ca
,
ca.
,
around
,
approximately
, or
approx.
:
- John Sayer
(
c.
?1750
?? 2
October 1818)
...
- the Igehalkid dynasty of Elam,
c.
?1400
BC
...
- Where both endpoints of a range are approximate,
c.
should appear before each date (the two-argument form of
{{
circa
}}
does this):
- Dionysius Exiguus
(
c.
?470
?? c.
?540
)
...
(not
Dionysius Exiguus
(
c.
470?? 540)
...
)
- Rameses III
(reigned
c.
?1180
?? c.
?1150
BCE
)
...
(not
Rameses III
(reigned
c.
1180?? 1150
BCE)
...
)
- Where birth/death limits have been inferred from known dates of activity:
- Offa of Mercia
(before 734?? 26
July 796)
...
- Robert Menli Lyon
(1789?? after 1863)
...
- Ambrose Gwinnett Bierce
(June 24, 1842?? after December 26, 1913)
...
- When birth and death dates are unknown, but the person is known to have been active ("flourishing") during certain years,
fl.
,
[[Floruit|fl.]]
, or
{{
fl.
}}
may be used:
- Jacobus Flori
(
fl.
1571?1588) ...
- Jacobus Flori
fils
(fl.
c.
?1600
?? 1616
) ...
- The corresponding template
{{
r.
}}
produces reign output:
r.
?540?562
, though it is often clearer to write out
reigned 540?562
, especially in the lead. With both of these templates, linked forms should not be used on disambiguation pages, and "active" followed by the range is a better alternative for occupations not relating to the composition of works, whether it be musical, grammatical, historical, or any other such work.
- When a date is known to be either of two years (e.g. from a
regnal
or
AH
year conversion, or a known age at death):
- Anne Smith
(born 1912 or 1913; died 2013)
...
- Other forms of uncertainty should be expressed in words, either in article text or in a footnote:
April
14, 1224 (unattested date)
. Do not use a question mark (
1291?
), because it fails to communicate the nature of the uncertainty.
- Where
c.
or a similar form appears
which applies only to one of the two endpoints of the range
, use a spaced en dash (
{{snd}}
).
- Examples
:
1896?? after 1954
,
470??
c.
?540
,
c.
?470
?? 540
,
c.
?470
?? c.
?540
.
- Markup
:
1896{{snd}}after 1954
,
470{{snd}}{{c.|540}}
,
{{c.|470}}{{snd}}540
,
{{c.|470|540}}
.
- Where a modifier
applies to the range as a whole
, such as
fl.
and
r.
, use a spaced or unspaced en dash as appropriate to the range if this modifier is disregarded.
- Examples
:
fl.
1571?1588
,
fl.
c.
?1600
?? 1616
,
r.
c.
?1353
???1336
BC
,
r.?1989?2019
CE
,
r.?2019
CE???present
.
- Some modifiers, such as
traditionally
,
around
,
BH
, and
CE
, sometimes apply to only one endpoint, and sometimes to the whole range. Whether the en dash should be spaced or unspaced should still be determined by the above guidelines, but consider rephrasing if the result is ambiguous or possibly confusing.
- traditionally 1571?1588
and
traditionally 1571?? 1588
mean two different things, which may not be obvious to the reader.
- traditionally 1585??
c.
?1590
can have two different meanings, and which one is meant may not be clear.
- 400 BCE?? 200
clearly has
BCE
applying only to one endpoint, but the range is ambiguous. Consider using
400?200 BCE
,
400 BCE?? 200 BCE
, or
400 BCE?? 200 CE
, depending on what is meant.
- Technically,
Taish?
13?? 57
is currently unambiguous (because there is no Taish? 57), but it is better to use both era designations in this case:
Taish?
13??
Sh?wa
57
.
- Ideally a non-breaking space should follow very short modifiers such as
c.
,
fl.
,
r.
,
b.
, and
d.
Times of day
[
edit
]
Context determines whether the
12-
or
24-hour
clock is used. In all cases, colons separate hours, minutes, and (where present) seconds, e.g.
1:38:09
pm
or
13:38:09
. Use figures (
11
a.m.
or
12:45
p.m.
) rather than words (
twelve forty-five p.m.
).
- 12-hour clock times
end with lower-case
a.m.
or
p.m.
, or
am
or
pm
, preceded by a
non-breaking space
, e.g.
2:30
p.m.
or
2:30
pm
(markup:
2:30
{{
nbsp
}}
p.m.
or
2:30
{{
nbsp
}}
pm
), not
2:30p.m.
or
2:30pm
. Hours should not have a leading zero (e.g.
2:30
p.m.
, not
02:30
p.m.
). Usually, use
noon
and
midnight
rather than
12 pm
and
12 am
; whether "midnight" refers to the start or the end of a date should be explicitly specified unless clear from the context. Where several times that are all a.m. or all p.m. appear in close proximity, then
a.m.
or
p.m.
need be given only once if there is no risk of confusion.
- 24-hour clock times
have no a.m., p.m., noon or midnight suffix, and include a colon (
15:30
not
1530
). Hours under 10 should have a leading zero (
08:15
). The time
00:00
refers to midnight at the start of a date,
12:00
to noon, and
24:00
to midnight at the end of a date, but
24
should not be used for the first hour of the next day (e.g. use
00:10
for ten minutes after midnight, not
24:10
).
Time zones
[
edit
]
Give dates and times appropriate to the
time zone
where an event took place. For example, the date of the
attack on Pearl Harbor
should be December
7, 1941 (Hawaii time/?date). Give priority to the place at which the event had its most significant effects; for example, if a hacker in Monaco attacked a Pentagon computer in the US, use the time zone for the Pentagon, where the attack had its effect. In some cases, the best solution may be to add the date and time in
Coordinated Universal Time
(UTC). For example:
8
p.m.
Eastern Standard Time
on January
15, 2001 (01:00
UTC, January
16)
Alternatively, include just the
UTC offset
:
21:00
British Summer Time
(
UTC+1
) on 27
July 2012
Rarely, the time zone in which an event took place has since changed; for example, China until 1949 was divided into
five time zones
, whereas all of modern China is one time zone;
UTC+8
. Similarly, the term "UTC" is not appropriate for dates before this system was adopted in 1960;
[2]
Universal Time
(UT) is the appropriate term for the mean time at the
prime meridian (Greenwich)
when it is unnecessary to specify the precise definition of the time scale. Be sure to show the UTC or offset appropriate to the clock time in use at the time of the event, not the modern time zone, if they differ.
Days of the week
[
edit
]
- Where space is limited (e.g. tables), days of the week may be abbreviated as
Sun
,
Mon
,
Tue
,
Wed
,
Thu
,
Fri
,
Sat
(without dots, i.e. not
Sun
.
,
Mon
.
, etc.).
Seasons of the year
[
edit
]
- Do not use seasons to refer to a particular time of year (
winter 1995
) as this would be ambiguous; the seasons are six months apart in the northern and southern hemispheres; winter in the northern hemisphere spans two calendar years, as does summer in the southern hemisphere; and areas near the equator have only
wet
and
dry seasons
. Unambiguous alternatives include
early?1995
;
the first quarter of 1995
;
January to March?1995
;
spent the southern summer in Antarctica
.
- Referring to a season by name is appropriate when it is part of a conventional name or designation (
annual mid-winter festival
;
the autumn harvest
;
the court's winter term
;
the magazine's summer 2015 issue
).
- Season names are generally not capitalized (
a hot summer
), except when personified (
Old Man Winter
) or when part of a formal name (
2018?Winter Olympics
;
Arab Spring
) that is capitalized under the
guidelines for capitalization
. They are capitalized when part of the title of a work (
Science Fiction Quarterly
, Summer 1942
), except that seasonal editions may be lower-cased in running text (
the Summer 1985 issue of
Interzone
or
the summer 1985 issue of
Interzone
).
Decades
[
edit
]
- To refer to a decade as a chronological period
per se
(not with reference to a social era or cultural phenomenon), always use four digits and an
s
, as in
the
1980s
. Do not use
the
1980's
, or
the
1980?ies
.
- Prefixes should be hyphenated (
the
mid?1980s
;
pre?1960s social attitudes
).
- Adjectives should not be hyphenated (
the late 1950s, the early 1970s
).
- For a social era or cultural phenomenon associated with a particular decade:
- Two digits (with a preceding apostrophe) may be used as an alternative to four digits, but only in well-established phrases seen in reliable sources:
the
Roaring
'20s
;
the
Gay
'90s
;
condemning the '60s counterculture
?but
grew up in 1960s Boston, moving to Dallas in
1971
. Do not write:
the
90's
;
the
90s
; or
the
90s'
.
- Another alternative (where seen in reliable sources) is to spell the decade out, capitalized:
changing attitudes of the Sixties
.
Centuries and millennia
[
edit
]
The sequence of numbered years in dates runs
...
2
BC, 1
BC, 1
AD, 2
AD
...
; there is no "
year zero
".
- Treat the 1st century AD as years
1?100
, the 17th century as
1601?1700
, and the second millennium as
1001?2000
; similarly, the 1st century BC/BCE was
100?1
BC/BCE, the 17th century BC/BCE was
1700?1601
BC/BCE, and the second millennium
2000?1001
BC/BCE.
- Centuries and millennia are identified using either Arabic numerals (
the 18th century
) or words (
the second millennium
), with in-article consistency (
MOS:ORDINAL
notwithstanding). When used adjectivally they contain a hyphen (
nineteenth-century painting
or
19th-century
painting
). Do not use superscripts (
19
th
century
).
- Do not capitalize (
the best Nineteenth-century paintings
;
during the Nineteenth Century
)
- Do not use
Roman numerals
(
XVIII
century
).
- The 18th century
refers to the period (
1701?1800
), while strictly
the 1700s
refers either to (
1700?1799
) or (
1700?1709
)
- When using forms such as
the 1900s
, ensure there is no ambiguity as to whether the century or the decade is meant.
- See
WP:Manual of Style §?En dashes
for use of hyphens and dashes in obscure situations.
Long periods of time
[
edit
]
- When the term is frequent, combine
yr
(years) or
ya
(years ago) with
k
(thousand):
kya
,
kyr
;
M
(million):
Mya
,
Myr
; and
b
(
short-scale
billion):
bya
,
byr
.
(See
Year §?Abbreviations yr and ya
for more information.)
- In academic contexts,
annus
-based units are often used with an
SI prefix
:
ka
(kiloannus),
Ma
(megaannus), and
Ga
(gigaannus).
(See
Year §?SI prefix multipliers
for more information.)
- Show the meaning parenthetically, and consider linking to the appropriate section of the
Year
article
(
Year §?Abbreviations yr and ya
or
Year §?SI prefix multipliers
)
on first occurrence and where the use is a standalone topic of interest. In source quotations, use square brackets:
"a potassium-argon date of 35.1
Mya [million years ago]
..."
"MOS:FIGURE" redirects here. Not to be confused with
MOS:IMAGE
.
Numbers as figures or words
[
edit
]
Information on specific situations is scattered elsewhere on this page.
Generally, in article text:
- Integers from zero to nine are spelled out in words.
- Integers greater than nine
expressible in one or two words
may be expressed either in numerals or in words (
16
or
sixteen
,
84
or
eighty-four
,
200
or
two hundred
). When written as words, integers from 21 to 99 that are not multiples of 10 are hyphenated (including when part of a larger number):
fifty-six
and
fifty-six thousand
, but
five
hundred
and
five
thousand
.
Notes and exceptions:
- Avoid beginning a sentence with a figure:
- Use:
There were many matches
;
23 ended in a draw.
Or:
There were many matches
.
Twenty-three ended in a draw.
- Not:
There were many matches
.
23 ended in a draw.
- Use:
No elections were held in 1945 and 1950.
- Not:
1945 and 1950 had no elections.
(Nor:
Nineteen forty-five and 1950 had no elections
?
comparable numbers should be both written in words or both in figures.)
- In tables and infoboxes, quantities are expressed in figures (
Years in office:
5
); but numbers within a table's explanatory text and comments follow the general rule.
- Numbers in mathematical formulae are never spelled out (
3 < π <
22
/
7
not
three < pi < twenty-two sevenths
), and "numbers as numbers" are rarely spelled out in other mathematical contexts (
the first three primes are 2, 3, and 5
not
the first three primes are two, three, and five
; but
zero-sum game
and
roots of unity
).
- Sport scores and vote tallies should be given as numerical figures (
a
25?7
victory
;
passed with 7 ayes, 2 nays, and 1 abstention
, though
passed with 7 ayes, 2 nays, and no abstentions
would be acceptable, instead of
...?0 abstentions
).
- Comparable values nearby one another should be all spelled out or all in figures, even if one of the numbers would normally be written differently:
patients' ages were five, seven, and thirty-two
or
ages were
5, 7, and
32
, but not
ages were
five, seven, and 32
.
- Similar guidance applies where "mixed units" are used to represent a single value (as is often done with time durations, and in the imperial and US customary systems):
5 feet 11 inches
tall
;
five feet eleven inches
tall
;
3 minutes 27 seconds
;
three minutes twenty-seven seconds
.
- Adjacent quantities not comparable should ideally be in
different formats:
twelve 90-minute volumes
or
12 ninety-minute volumes
, not
12 90-minute volumes
or
twelve ninety-minute volumes
.
- Avoid awkward juxtapositions:
On February 25, 2011, twenty-one more were chosen
, not
On February 25, 2011, 21 more were chosen
.
- Sometimes figures and words carry different meanings; for example,
Every locker except one was searched
implies there is a single exception (without specifying which), while
Every locker except
1 was searched
implies that locker number
1 was the only locker not searched.
- Proper names, technical terms, and the like are never altered:
10 Downing Street
,
Nine Inch Nails
,
Channel 8
,
Seven Samurai
,
The Sixth Sense
,
Chanel No.?5
,
Fourth Estate
,
The Third Man
,
Second Coming
,
First Amendment
,
Zero Hour!
,
"
Less than Zero
",
C7 vertebra
.
- Figures as figures: Use a figure when the figure itself (its
glyph
, shape, etc.) is meant:
a figure-8 pattern
;
in the shape of the numeral
6
.
(See
Wikipedia:Manual of Style/Text formatting §?Words as words
.)
- Only figures are used with unit
symbols
(
12 min
not
twelve min
); but figures or words may be used with unit
names
(
12 minutes
or
twelve minutes
), subject to the provisions above.
Other numbers
- Other numbers are given in numerals (
3.75
,
544
) or in forms such as
21
million
(or
billion
,
trillion
, etc.?? but rarely
thousand
or
hundred
). Markup:
21{{nbsp}}million
- Billion
and
trillion
are understood to represent their
short-scale
values of 10
9
(1,000,000,000) and 10
12
(1,000,000,000,000), respectively. Keep this in mind when translating articles from non-English or older sources.
- M
(unspaced, capitalized) or
bn
(unspaced), respectively, may be used for "million" or "billion" after a number, when the word has been spelled out at the first occurrence (
Her estate of £61
million was split among her husband (£1M), her son (£5M), her butler (£10M), and her three Weimaraners (£15M each).
).
- SI prefixes and symbols, such as
mega-
(
M
),
giga-
(
G
) and
tera-
(
T
), should be used only with units of measure as appropriate to the field and not to express large quantities in other contexts. Examples of misuse:
In a population of 1.3G
people, 300
megadeaths would be expected.
- Sometimes, the
variety of English
used in an article may suggest the use of a numbering system other than the Western thousands-based system. For example, the
Indian numbering system
is conventionally used for certain things (especially monetary amounts) in
South Asian English
. This is discouraged in Wikipedia articles by
WP:Manual of Style §?Opportunities for commonality
.
- When it is done anyway, for contextually important reasons, link the first spelled-out instance of each quantity (e.g.
[[crore]]
, which yields:
crore
). If no instances are spelled out, provide a note after the first instance, directing the reader to the article about the numbering system.
- Provide a conversion to Western numbers for the first instance of each quantity (For Indian figures, the templates
{{
lakh
}}
and
{{
crore
}}
may be used for this purpose), and provide conversions for subsequent instances if they do not overwhelm the content of the article. For example, write
three
crore
(thirty million)
. When converting a currency amount, use the exchange rate that applied at the time being written about; the
{{
FXConvert
}}
template can be used for this purpose, or specialized templates for a currency such as
{{
INRConvert
}}
(for Indian Rupees) or
{{
KRWConvert
}}
(for Korean Won) can be used.
- Group digits in Western thousands-based style (e.g.,
30,000,000
; not
3,00,00,000
);
see
§?Delimiting (grouping of digits)
, below
.
- An article's variety of English does not uniquely determine its formatting of numbers. Other considerations?? such as conventions used in mathematics, science, and engineering?? may also apply. In general, choice and order of formats and conversions is a matter of editorial discretion and consensus at the article.
Ordinals
[
edit
]
"MOS:1ST" redirects here. For the guideline on the first sentence in articles, see
MOS:FIRST
.
- The general principles set out in
§?Numbers as figures or words
apply to ordinals. In particular, do not start a sentence with a figure, and generally use
first
through
ninth
, not
1st
through
9th
, for single-digit ordinals.
- In "suffix" forms, use two-letter suffixes:
1st, 2nd, 3rd, 4th
and so on (
2nd
Battalion
not
2d
Battalion
). Do not superscript (e.g.
123
rd
).
- Do not use ordinals for dates (see
MOS:BADDATE
).
- In English text, do not use a dot (
.
) or the
ordinal indicator
(
º
). The masculine
º
or feminine
ª
ordinal indicator is acceptable in names, quotations, etc. from languages that conventionally use it. An Italian example:
313º Gruppo Addestramento Acrobatico
not
313º Acrobatic Training Group
or
the 313º
. Use HTML markup for languages that do not have a special character but conventionally use a superscript, like
2
e
in French.
- Regnal numbers
are normally written with ASCII
Roman numerals
(without suffix, e.g.
Elizabeth II
not
Elizabeth IInd
or
Elizabeth 2nd
).
Number ranges
[
edit
]
Like
date ranges
, number ranges and page ranges should state the full value of both the beginning and end of the range, separated by an
en dash
:
pp.
1902?1911
or
entries
342?349
. Except within quotations, avoid abbreviated forms such as
1902?11
or
342?9
, which are not understood universally, are sometimes ambiguous, and can cause inconsistent metadata to be created in citations.
Sport scores, vote tallies, etc.
[
edit
]
These use an unspaced en dash, directly or with the template
{{
en dash
}}
AKA
{{
ndash
}}
:
- Smith beat Jones
7?3
.
- Polls predicted Alice would defeat Bob
74?20
percent, with 6 percent undecided.
To avoid potential line breaks, use
{{
nowrap
}}
around the entire score construction, or use
{{
nbnd
}}
between scores instead of
{{
ndash
}}
.
Singular versus plural
[
edit
]
- Nouns following
simple fractions
are singular (
took
1
?
4
dose
;
net change was ?
1
?
2
point
;
3
?
2
dose
).
- Nouns following
mixed numbers
are plural (
1
1
?
2
doses
;
another 4
3
?
4
miles
).
- Nouns following the lone, unsigned digit 1 (one) are singular, but those following other decimal numbers (i.e. base-10 numbers not involving fractions) are plural (
increased 0.7 percentage points
;
365.25?days
;
paid 5 dollars per work hour, 1 dollar per travel hour, 0 dollars per standby hour
;
increased by 1?point
but
net change +1?points
;
net change ?1?points
;
net change 1.0?points
).
- The same rules apply to numbers given in words (
one dose
;
one and one-half doses
;
zero dollars
;
net change of negative one points
).
Fractions and ratios
[
edit
]
- Where numerator and denominator can each be expressed in one word, a fraction is usually
spelled out
(e.g.
a two-thirds majority
;
moved one-quarter mile
); use figures if a fraction appears with a symbol (e.g.
1
?
4
mi
(markup:
{{frac|1|4}}
mi
), not
a quarter of a mi
or
one-quarter mi
). A common exception is a series of values:
The distances were
1
+
1
?
4
,
2
?
3
and
1
?
2
mile, respectively
.
- Mixed numbers
may be given in figures or words (perhaps applying the guidance
above
to the integer part). If given in figures, they are unspaced (not
Platform 9
3
?
4
or
Platform 9-
3
?
4
but
Platform
9
+
3
?
4
(markup:
{{frac|9|3|4}}
)). In any case the integer and fractional parts should be consistent (not
Platform nine and
3
?
4
).
- Metric (SI) measurements generally use decimals, not fractions (
5.25
mm
, not
5
1
?
4
mm
).
- Non-metric (imperial and US customary) measurements may use fractions or decimals (
5
1
?
4
inches
;
5.25
inches
); the practice of reliable sources should be followed, and within-article consistency is desirable.
- In science and mathematics articles, mixed numbers are rarely used (use
4
/
3
the original
rather than
1
1
/
3
times the original voltage
). The use of
{{
frac
}}
is discouraged
; instead use one of these styles:
- (markup:
<
math
>\textstyle\frac{1}{2}</math>
)
- 1
/
2
(markup:
{{
sfrac
|1|2}}
)
- 1/2
(markup:
1/2
)
- Do not use
precomposed fraction
characters such as
½
(deprecated markup:
½
or
½
).
[k]
- Except: If ¼, ½, and ¾
[l]
are the only fractions needed, they may be used in an article, or category name, maintaining typographical consistency within an article where possible. (Examples:
Floppy disk
,
Ranma ½
,
chess notation
,
Category:4 ft 6½ in gauge railways?
.)
- For other fractions, where templates cannot be used due to technical limitations, use the ASCII representation with spaces. For example,
Category:4 ft 10 7/8 in gauge railways
.
- Ordinal suffixes such as
-th
should not be used with fractions expressed in figures (not
each US state has 1/50th of the
Senate's
votes
;
1/8th mile
, but
one-fiftieth of the
Senate's
votes
;
1/8 mile
;
one-eighth mile
).
- For dimensionless ratios (i.e. those without accompanying units), place a colon between integers, or place
to
between numbers-as-words:
favored by a 3:1 ratio
or
a three-to-one ratio
, not
a 3/1 ratio
or
a 3?1 ratio
.
The same style is used to express
odds
in sport, gambling, and other statistical predictions.
- Use a colon (spaced) when one or more decimal points is present
(
a 3.5?:?1 ratio
(markup:
a 3.5 : 1 ratio
)).
- Do not use the colon form where units are involved (
dissolve using a
3 ml?: 1 g ratio
)???instead see
ratios
section of table at
§?Unit names and symbols
, below.
Decimals
[
edit
]
- Use a period/full point (
.
) as the
decimal separator
,
never
a comma:
6.57
, not
6,57
.
- Numbers between ?1 and +1 require a leading zero (
0.02
, not
.02
); exceptions are sporting performance averages (
.430
batting average
) and conventional terms such as
.22
caliber
.
- Although repeating digits may be indicated with an
overbar
(e.g.
14.31{{overline|28}}
gives
14.31
28
), users of screen readers will not hear any indication of the overbar. Apart from in mathematics articles, consider rounding to a reasonable resolution instead (e.g. a
half farthing
?£0.00052
not
£0.0005208
3
, an
inch
?0.333
palms
not
0.
3
palms
), or showing initial repeats before the overbar (e.g. 0.33
3
). If overbars are used, consider explaining the notation on first use. Do not write e.g.
14.31(28)
because it resembles
notation for uncertainty
.
Grouping of digits
[
edit
]
- In general, digits should be grouped and separated either by commas or by narrow gaps (
never
a period/full point).
- Grouping with commas
- Left of the decimal point, five or more digits are grouped into threes separated by commas (e.g.
12,200
;
255,200?km
;
8,274,527th
;
1
?
86,400
).
- Numbers with exactly four digits left of the decimal point may optionally be grouped (either
1,250
or
1250
), consistently within any given article.
- Do not use commas to the right of the decimal point, or with numbers not in base 10.
- Markup:
{{
formatnum:
}}
produces this formatting.
- Grouping with narrow gaps
- Digits are grouped both sides of the decimal point (e.g.
6
543
210
.123
456
;
520.012
34
?°C
;
101
325
/
760
).
- Digits are generally grouped into threes. Right of the decimal point,
usual
practice is to have a final group of four in preference to leaving an "orphaned" digit at the end (
99.123
4567
, but
99.123
456
7
would also be acceptable). In mathematics-oriented articles long strings may be grouped into fives (e.g.
3.14159
26535
89793
23846
...
).
- This style is especially recommended for articles related to science, technology, engineering or mathematics, though in these contexts there may be cases in which grouping confuses rather than clarifies. (For example, for fractions written in horizontal format, adding spaces to a fraction like 123456/127 would cause it to be misread as 123
456
/
127
or 1
23456
/
127
.)
- Markup: Templates
{{
val
}}
or
{{
gaps
}}
may be used to produce this formatting. Note that use of
any
space character as a separator in numbers, including non-breaking space, is problematic for
screen readers
.
(See
§?Non-breaking spaces
.)
Screen readers read out each
group
of digits as separate numbers (e.g.
30
{{
thin space
}}
000
is read as "thirty zero zero zero"). The output of
{{
val
}}
and
{{
gaps
}}
is compatible with screen readers.
- Delimiting style should be consistent throughout a given article.
- Either use commas or narrow gaps, but not both in the same article.
- Either group the thousands in a four-digit number or do not, but not mixed use in the same article.
- However, grouping by threes and fives may coexist.
- Four-digit page numbers and four-digit calendar years should never be grouped (not
sailed in 1,492
, but
dynasty collapsed around 10,400?BC
or
by
13
727
?AD
, Vega will be the northern pole star
).
Percentages
[
edit
]
- Throughout scientific/?technical articles, and in tables and infoboxes in
any
article, the symbol
%
is generally preferred. No space (
3%
, not
3
%
), and do not use mixed forms such as
three
%
.
- The body
[h]
of non-scientific/?non-technical articles may use either the
%
symbol or the word(s)
percent
(American English) or
per
cent
(British English):
10 percent
;
ten percent
;
4.5 per cent
.
- Ranges are written
10?12%
,
ten to twelve per cent
, or
ten to twelve percent
; not
ten?twelve per cent
,
10%?12%
, or
10 to 12%
.
- When expressing the difference between two percentages, do not confuse a percentage change with a change in
percentage points
.
Scientific and engineering notation
[
edit
]
- Scientific notation
always has a single nonzero digit to the left of the point: not
60.22
×
10
22
, but
6.022
×
10
23
.
- Engineering notation
is similar, but with the exponent adjusted to a multiple of three:
602.2
×
10
21
.
- Avoid mixing scientific and engineering notations:
A
2.23
×
10
2
?m
2
region covered by
234.0
×
10
6
?grains of sand
.
- In a table column (or other presentation) in which all values can be expressed with a single power of 10, consider giving e.g.
×
10
7
once in the column header, and omitting it in the individual entries. (Markup:
{{e|7}}
)
- In both notations, the number of digits indicates the precision. For example,
5
×
10
3
means rounded to the nearest thousand;
5.0
×
10
3
to the nearest hundred;
5.00
×
10
3
to the nearest ten; and
5.000
×
10
3
to the nearest unit.
Markup:
{{
val
}}
and
{{
e
}}
may be used to format exponential notation.
Uncertainty and rounding
[
edit
]
- Where explicit uncertainty information (such as a
margin of error
) is available and appropriate for inclusion, it may be written in various ways:
- (1.534 ± 0.035) × 10
23
m
- 12.34
m
2
± 5%
(not used with scientific notation)
- 15.34
+0.43
?0.23
× 10
23
m
- 1.604(48) × 10
?4
J
(equivalent to
(1.604 ± 0.048) × 10
?4
J
)
[m]
- Polls estimated Jones's share of the vote would be 55 percent, give or take about 3 percent
- Markup:
{{
+-
}}
,
{{
su
}}
, and
{{
val
}}
may be used to format uncertainties.
- Where explicit
uncertainty is unavailable
(or is unimportant for the article's purposes), round to an appropriate number of
significant digits
; the precision presented should usually be conservative. Precise values (often given in sources for formal or matter-of-record reasons) should be used only where stable and appropriate to the context, or significant in themselves for some special reason.
- The speed of light is defined to be 299,792,458
m/s
- but
Particle velocities eventually reached almost two-thirds the 300-million-metre-per-second speed of light.
- checks worth $250 (equivalent to $1,800 in 2016)
(not
$1,845.38 in 2016
)
- The city's 1920 population was 10,000
(not
population was 9,996
?? an official figure unlikely to be accurate at full precision)
- but
The town was ineligible because its official census figure (9,996) fell short of the statutory minimum of ten thousand
(unusual case in which the full-precision official figure is truly informative)
- The accident killed 337 passengers and crew, and 21 people on the ground
(likely that accurate and precise figures were determined)
- At least 800 persons died in the ensuing mudslides
(unlikely that any precise number can be accurate, even if an official figure is issued)
- or
Officials listed 835 deaths, but the Red Cross said dozens more may have gone unreported
(in reporting conflicting information, give detail sufficient to make the contrast intelligible)
- The jury's award was $8.5
million
(not
$8,462,247.63
).
The appeals court reduced this to $3,000,001 (one dollar in actual damages, the remainder in punitive damages).
- The number of decimal places should be consistent within a list or context (
The response rates were 41.0 and 47.4 percent, respectively
, not
41 and 47.4 percent
), unless different precisions are actually intended.
- It may sometimes be appropriate to note the
lack
of uncertainty information, especially where such information is normally provided and necessary for full interpretation of the figures supplied.
- A local newspaper poll predicted 52 percent of the vote would go to Smith, but did not include information on the uncertainty of this estimate
- The
{{
undue precision
}}
template may be added to figures appearing to be overprecise.
- Avoid using "approximately", "about", and similar terms with figures that have merely been approximated or rounded in a normal and expected way, unless the reader might otherwise be misled.
- The tallest player was 6 feet 3 inches
(
not
... about 6 feet 3 inches
?? heights are conventionally reported only to the nearest inch, even though greater precision may be available in principle)
- but
The witness said the assailant was about 5 feet 8 inches tall
("about" because here the precise value is unknown, with substantial uncertainty)
- The reader may be assumed to interpret large round numbers (
100,000 troops
) as approximations. Writing a quantity in words (
one hundred thousand troops
), especially if the
indefinite article
(
a
/
an
) is used instead of the word
one
(
a hundred thousand troops
), can further emphasize its approximate nature.
- See
§?Unit conversions
below for precision issues when converting units.
Non?base-10 notations
[
edit
]
- In computer-related articles, use the prefix
0x
for hexadecimal and
0b
for binary,
[n]
unless there is a strong reason to use some other notation.
[o]
Explain these prefixes in the article's introduction or on first use.
- In all other articles, use base: 137
9
, 201
3
. Markup:
{{base|137|9}}
,
{{base|201|3}}
- For
bases
above 10, use symbols conventional for that base (as seen in reliable sources) e.g. for
base 16
use
0?9 and A?F
.
- For octal, use 200
8
. Avoid using a prefix unless it is needed for computer code samples, in which case explain the prefix on first use.
Mathematical formulae
[
edit
]
There are multiple ways to display mathematical formulae, covered in detail at
Wikipedia:Manual of Style/Mathematics §?Typesetting of mathematical formulae
. One uses special MediaWiki
<math>...</math>
markup using
LaTeX
syntax, which is capable of complex formulae; the other relies on conventionalized
HTML
formatting of simple formulae.
The
<math>
markup is displayed as a
PNG
image by default. Logged-in users can optionally have it rendered in
MathML
, or in HTML (via
MathJax
); detailed instructions are at
Help:Displaying a formula
.
Do not put
<math>
markup in headings
.
Unit choice and order
[
edit
]
Quantities are typically expressed using an appropriate "primary unit", displayed first, followed, when appropriate, by a conversion in parentheses e.g.
200 kilometres (120?mi)
. For details on when and how to provide a conversion, see the section
§?Unit conversions
. The choice of primary units depends on the circumstances, and should respect the principle of "
strong national ties
", where applicable:
- In
non-scientific articles with strong ties to the United States
, the primary units are
US customary
(pounds,
miles
, feet, inches, etc.)
- In
non-scientific articles with strong ties to the United Kingdom
, the primary units for most quantities are metric or other internationally used units,
[p]
except that:
- UK engineering-related articles, including those on bridges and tunnels, generally use the system of units in which the subject project was
drawn up
(but road distances are given in imperial units, with a metric conversion?? see next bullet);
- the primary units for distance/?length, speed and fuel consumption are
miles
, miles per hour, and miles per imperial gallon (except for short distances or lengths, where miles are too large for practical use);
- the primary units for personal height and weight are feet?/inches and stones/?pounds;
- imperial pints are used for quantities of draught beer/?cider and bottled milk;
- In
all other articles
, the primary units chosen will be
SI
units (such as kilograms),
non-SI units officially accepted for use with the SI
, or such other units as are conventional in reliable-source discussions of the article topic (such as
revolutions per minute
(rpm) for
rotational speed
,
hands
for heights of horses, etc.)
- the primary SI units for personal height and weight are centimetres and kilograms.
Special considerations:
- Quantities set via definition (as opposed to measured quantities) should be given first in the units used in the definition, even if this makes the structure of presentation inconsistent:
During metrication, the speed limit was changed from 30
mph (48
km/h) to 50
km/h (31
mph)
.
- Or use
about
to emphasize which is the statutory, exact value:
...from 30
mph (about 48
km/h) to 50
km/h (about 31
mph)
.
- Nominal quantities (e.g.
2
×
4
lumber
) require consideration of whether the article is concerned with the item's actual dimensions or merely with its function. In some cases, the nominal quantity may suffice; in others it may be necessary to give the nominal size (often in non-SI units), the actual size in non-SI units, and the actual size in SI units.
- Whenever a conversion is given, the converted quantity's value should match the precision of the source
(see
§?Unit conversions
)
.
- Where the article's primary units differ from the units given in the source, the
{{
convert
}}
template's
|order=flip
flag can be used; this causes the
original
unit to be shown as secondary in the article, and the
converted
unit to be shown as primary:
{{convert|200|mi|km|order=flip}}
→
The two cities are 320 kilometres (200?mi) apart.
Unit conversions
[
edit
]
Where English-speaking countries use different units for the same quantity, provide a conversion in parentheses:
the Mississippi River is 2,320 miles (3,734?km) long
;
the Murray River is 2,508 kilometres (1,558?mi) long
. But in science-related articles, supplying such conversion is not required unless there is some special reason to do so.
- Where an
imperial unit
is not part of the
US customary system
, or vice versa?? and in particular, where those systems give a single term different definitions?? a double conversion may be appropriate:
Rosie weighed 80 kilograms (180?lb; 12?st 8?lb)
(markup:
{{convert|80|kg|lb stlb}}
);
The car
had a fuel economy of 5?L/100?km (47?mpg
?US
; 56?mpg
?imp
)
(markup:
{{convert|5|L/100km|mpgus mpgimp|abbr=on}}
).
- Generally, conversions to and from metric units and US or imperial units should be provided, except:
- When inserting a conversion would make a common or linked expression awkward (
The four-minute mile
).
- In some topic areas (for example maritime subjects where nautical miles are the primary units, or American football where
yards
are primary) it can be excessive to provide a conversion for every quantity. In such cases consider noting that the article will use a particular unit?? possibly giving the conversion factor to other, familiar units in a parenthetical note or a footnote?? and link the first occurrence of each unit but not give a conversion every time it occurs. Applying this principle may require editorial discretion; for example, in scientific articles the expected level of reader sophistication should be taken into account.
- For units of measure that are obsolete, obscure outside of a particular specialty or geography (e.g.
furlong
), or not part of the SI or US customary systems (e.g.
zolotnik
), supply a parenthetical conversion into at least SI units. Convert each mention, unless this would be excessive given the context. Take care to distinguish between different definitions of the same unit if it has changed over time or differs geographically (e.g.
cubit
,
batman
). An approximate or range conversion is acceptable if the exact historical value is uncertain (e.g.
stadion
).
- Converted quantity values should use a
level of precision
similar to that of the source quantity value, so
the Moon is 380,000
kilometres (240,000
mi) from Earth
, not
(236,121
mi)
. Small numbers, especially if approximate, may need to be converted to a range where rounding would cause a significant distortion, so
about one mile (1?2
km)
, not
about one mile (2
km)
. Be careful especially when your source has already converted from the units you're now converting back to. This may be evidenced by multiples of common conversion factors in the data, such as 160 km (from 100 miles).
See
false precision
.
{{
convert
}}
and other
conversion templates
can be used to convert and format many common units, and have options to respect significant figures. To avoid problems with rounding and significant figures, for input to conversion templates use only the original quantity found in reliable sources, not one that a source has already converted. If required by the above rules, the conversion output can be displayed as the primary units with "order=flip". Conversion output can be displayed as the only units with "disp=out"; this retains the original quantity in wikitext for verification by editors.
- In a
direct quotation
, always retain the source units. Any conversions can be supplied either in the quote itself (in square brackets, following the original measurement) or in a footnote.
See
footnoting
and
citing sources
.
{{
Units attention
}}
may be added to articles needing general attention regarding choice of units and unit conversions.
Unit names and symbols
[
edit
]
- Definitions:
- Examples of
unit names
: foot, metre, kilometre, (
US:
meter, kilometer).
- Examples of
unit symbols
: ft, m, km.
- Unit names and symbols should follow the practice of reliable sources.
- In prose, unit names should be given in full if used only a few times, but symbols may be used when a unit (especially one with a long name) is used repeatedly, after spelling out the first use (e.g.
Up to 15 kilograms of filler is used for a batch of 250
kg
).
- Exception: Certain units are generally represented by their symbols (e.g.
°C
rather than
degrees Celsius
) even on first use, though their unit names may be used for emphasis or clarity (
conversion of degrees Celsius to degrees Fahrenheit
).
- Exception: Consider using
inches
(but not
in.
) in place of
in
where the latter might be misread as a preposition???but not where the value is followed by a parenthesized conversion e.g.
bolts 5?in (12.7?cm) long
, or is part of such a conversion (
bolts 12.7?cm (5?in) long
).
- Where space is limited, such as in tables, infoboxes, parenthetical notes, and mathematical formulas, unit symbols are preferred.
- Units unfamiliar to general readers should be presented as a name?symbol pair on first use, linking the unit name (
Energies rose from 2.3
megaelectronvolts
(MeV) to 6
MeV
).
- Ranges use unspaced en dash (
{{
ndash
}}
) if only one unit symbol is used at the end (e.g.
5.9?6.3
kg
), and spaced en dash (
{{
snd
}}
) if two symbols are used (e.g.
3
μm?? 1
mm
); ranges in prose may be specified using either unit symbol or unit names, and units may be stated either after both numerical values or after the last (all acceptable:
from 5.9 to 6.3 kilograms
;
from 5.9 kilograms to 6.3 kilograms
;
from 5.9 to 6.3
kg
;
from 5.9
kg to 6.3
kg
).
- Length?width, length?width?height and similar dimensions may be separated by the multiplication sign (
×
or
×
) or the word
by
.
- The
×
symbol is preceded by a space (preferably non-breaking), and followed by a space (which may also be non-breaking in short constructions), and each number should be followed by a unit name or symbol:
- 1 m × 3 m × 6 m
, not
1 × 3 × 6 m
,
(1 × 3 × 6) m
, nor
1 × 3 × 6 m
3
- a metal plate 1 ft × 3 ft × 0.25 in
- a railroad easement 10 ft × 2.5 mi
- With
by
, the unit need be given only once if it is the same for all dimensions:
1 by 3 by 6 metres
or
1 by 3 by 6 m
- The unspaced letter
x
may be used in common terms such as
4x4
.
General guidelines on use of units
Guideline
|
Acceptable
|
Unacceptable
|
Except as listed in the
§?Specific units
table below, unit
symbols
are uncapitalized unless they are derived from a proper name, in which case the first letter (of the base unit symbol, not of any prefix) is capitalized.
[q]
|
8 kg
100 kPa
|
8 Kg
100 kpa
|
Unit symbols are undotted.
|
38 cm of rope
|
38 cm
.
of rope
|
Unit
names
are given in lower case except: where any word would be capitalized, or where otherwise specified in the SI brochure
[4]
or this Manual of Style.
|
- A gallon is 4
quarts.
- 4 pascals
|
- A Gallon is 4
Quarts.
- 4 Pascals
|
- He walked several miles.
- Miles of trenches were dug.
|
|
The spelling of certain unit names (some of which are listed in
§?Specific units
, below) varies with the
variety of English followed by the article
.
|
|
|
Write unit names and symbols in upright (
roman
) type, except where emphasizing in context.
|
10
m
29 kilograms
|
10
m
29
kilograms
|
Thus each two-liter jug contained only two
quarts
.
|
|
Do not use precomposed unit symbol characters.
|
|
㎓, ㎦, ㎍, ㎖, ㎉
|
Do not spell out numbers before unit
symbols
...
|
12
min
|
twelve
min
|
...
but words
or
figures may be used with unit
names
.
|
- twelve minutes
- 12 minutes
|
|
Use a non-breaking space (
{{
nbsp
}}
or
) between a number and a unit
symbol
, or use
{{
nowrap
}}
...
|
29
kg
(markup:
29 kg
or
{{nowrap|29 kg}}
)
|
29kg
|
... though with certain symbols
no
space is used (see "Specific
units" table below)
...
|
23°
47′
22″
|
23
°
47
′
22
″
|
... and a normal space is used between a number and a unit
name
.
|
29
kilograms
(markup:
29?kilograms
)
|
|
To form a value and a unit
name
into a compound adjective use a hyphen or hyphens
...
|
- a five-day holiday
- a five-cubic-foot box
- a 10-centimeter blade
|
|
... but a non-breaking space (never hyphen) separates a value and unit
symbol
.
|
|
a 10-cm blade
|
SI
unit
names
are pluralized by adding
-s
or
-es
...
|
1 ohm
;
10 ohms
|
|
... except for these irregular forms.
|
1 henry
;
10 henries
1 hertz
;
10 hertz
1 lux
;
10 lux
1 siemens
;
10 siemens
|
10 henrys
10 hertzes
10 luxes
10 siemenses
|
Some non-SI units have irregular plurals.
|
1 foot
;
10 feet
|
10 foots
|
1 stratum
;
10 strata
(unusual)
|
10 stratums
|
Unit
symbols
(in any system) are identical in singular and plural.
|
- grew from 1 in to 2 in
- grew from 1 inch to 2 inches
- grew from one to two inches
|
grew from 1 in to 2 ins
|
Format exponents using <sup>, not special characters.
|
km
2
(markup:
km<sup>2</sup>
)
|
km²
(
km²
)
|
Or use
squared
or
cubed
(
after
the unit being modified).
|
ten metres per second squared
|
ten metres per squared second
|
For areas or volumes only,
square
or
cubic
may be used (
before
the unit being modified).
|
ten metres per square second
|
tons per square mile
|
|
sq
or
cu
may be used with US customary or imperial units, but not with
SI
units.
|
15
sq
mi
3
cu
ft
|
15
sq
km
3
cu
m
|
Indicate a product of unit
names
with either a hyphen or a space.
|
|
|
Indicate a product of unit
symbols
with
&
sdot
;
or
&
nbsp
;
.
|
- ms
= millisecond
- m?s
or
m
s
= metre-second
|
|
Exception:
In some topic areas, such as power engineering, certain products take neither space nor
⋅
. Follow the practice of reliable sources in the article's topic area.
|
|
|
To pluralize a product of unit
names
, pluralize only the final unit. (Unit
symbols
are never pluralized.)
|
ten foot-pounds
|
ten feet-pounds
|
Indicate a ratio of unit
names
with
per
.
|
meter per second
|
meter/second
|
Indicate a ratio of unit
symbols
with a forward slash (
/
), followed by either a single symbol or a parenthesized product of symbols?? do not use multiple slashes. Or use
?1
,
?2
, etc.
|
- metre per second
- m/s
- m?s
?1
|
|
|
|
To pluralize a ratio of unit
names
, pluralize only the numerator unit. (Unit
symbols
are never pluralized.)
|
- ten newton-metres per second
- 10 N?m/s
|
|
Some of the special forms used in the imperial and US customary systems are shown here
...
|
- mph
= miles per hour
- mpg
= miles per gallon
- psi
=
pounds
per square inch
|
|
... but only the slash or negative exponent notations are used with SI (and other metric) units.
|
|
gsm
|
|
kph
|
Prefixes should not be separated by a space or hyphen.
|
kilopascal
|
|
Prefixes are added without contraction, except as shown here:
|
kilohm
megohm
hectare
|
kiloohm
megaohm
hectoare
|
The
deci-
,
deca-
, and
hecto-
prefixes should generally be avoided; exceptions include decibel, hectolitre, hectare, and hectopascal.
|
|
1 hectometre
|
Do not use
M
for 10
3
,
MM
for 10
6
, or
B
for 10
9
(except as noted elsewhere on this page for
M
and
B
, e.g.
for monetary values
)
|
3 km
8 MW
125 GeV
|
3 Mm
8 MMW
125 BeV
|
Mixed units are traditionally used with the imperial and US customary systems
...
|
- a wall 1 ft 1 in thick
- a wall 1 foot 1 inch thick
- a man 6 feet 2 inches tall
- a 6-foot 2-inch man
- a 6 ft 2 in man
|
- 1 ft?, 1 in
(no comma)
- 1 foot?, 1 inch
- a man 6 foot 2 tall
- a 6-foot 2 man
-
|
- 1 US fl pt 8 oz
- 1 US fl pt 8 US fl oz
|
|
... and in expressing time durations
...
|
|
- 1:30′07″
- 1:30′
- 1 hr 30 min 7 sec
- 1 h 30 m 7 s
|
... but are not used with metric units.
|
|
1 m 33 cm
|
Note to table:
- ^
Use this format only where it is clear from context whether it means hours and minutes (HH:MM) or minutes and seconds (MM:SS).
- ^
This format is used in astronomy (see the IAU Style Manual
[6]
for details).
Specific units
[
edit
]
- The following table lists only units that need special attention.
- The
SI Brochure
[4]
should be consulted for guidance on use of other SI and non-SI units.
Guidelines on specific units
Unit name
|
Unit symbol
|
Comment
|
|
|
Do not use
′
(
′
),
″
(
″
), apostrophe
(
'
), or quote
(
"
). Exception: in music,
eight-foot pitch
notation describes organ stops and wind instrument lengths in feet. A prime may be used with an explanation on first use, e.g.
a
16 foot
(16′) organ pedal stop
; see
MOS:MUSIC
.
|
foot per second
|
ft/s
(
not
fps
)
|
|
hand
|
h
or
hh
|
Equal to 4 inches; used in measurement of horses. A dot may be followed by additional inches e.g.
16.2 hh
indicates
16 hands 2 inches.
|
|
- kn
(
not
kt
,
Kt
, or
kN
)
- KIAS
or
kn
- KCAS
- KEAS
- KTAS
- kn
(
not
KGS
)
|
Used in aviation contexts for aircraft and wind speeds, and also used in some nautical and general meteorological contexts. When applied to aircraft speeds,
kn
means
KIAS
unless stated otherwise; if
kn
is used for calibrated airspeed, equivalent airspeed, true airspeed, or groundspeed, explicitly state and link to, upon first use, the type of speed being referred to (for instance,
kn
equivalent airspeed
, or, if severely short of space,
kn
EAS
); for airspeeds other than indicated airspeed, the use of the specific abbreviation for the type of airspeed being referred to (such as
KEAS
) is preferred. When referring to indicated airspeed, either
kn
or
KIAS
is permissible. Groundspeeds and wind speeds
must
use the abbreviation
kn
only.
|
|
m
|
|
micron
|
μm
(
not
μ
)
|
Markup:
μm
Link to
micrometre
(for which micron is a synonym) on first use.
|
astronomical unit
|
au
(
not
A.U.
,
ua
)
|
The preferred form is
au
. Articles that already use
AU
may switch to au or continue with AU; seek consensus on the talk page.
|
- mile
- miles per hour
- nautical mile
|
- mi
- mph
- nmi
or
NM
(
not
nm
or
M
)
|
In nautical and aeronautical contexts where there is risk of confusion with nautical miles, consider writing out references to
statute miles
as e.g.
5
statute
miles
rather than simply
5
miles
.
|
- cubic centimetre
- cubic centimeter
(US)
|
cm
3
|
Markup:
cm<sup>3</sup>
|
cc
|
Non-SI abbreviation used for certain
engine displacements
. Link to
Cubic centimetre
on first use.
|
- imperial fluid ounce
- imperial pint
- imperial quart
- imperial gallon
- US fluid ounce
- US dry pint
- US liquid pint
- US dry quart
- US liquid quart
- US gallon
|
- imp fl oz
- imp pt
- imp qt
- imp gal
- US fl oz
- US dry pt
- US liq pt
- US dry qt
- US liq qt
- US gal
|
- US
or
imperial
(or
imp
) must be specified for all these units.
- fluid
or
fl
must be specified for fluid ounces (to avoid ambiguity versus
avoirdupois ounce
and
troy ounce
).
- For US pints and quarts,
dry
or
liquid
(
liq
) are needed to be fully unambiguous, though context determines whether or not to repeat those qualifiers on every use in a given article.
|
cubic foot
|
cu ft
(
not
cf
)
|
Write
five million cubic feet
,
5,000,000
cu
ft
, or
5
×
10
6
?cu?ft
, not
5
MCF
.
|
cubic foot per second
|
cu ft/s
(
not
cfs
)
|
|
|
L
(
not
l
or
ℓ
)
|
The symbol l (lowercase "el") in isolation (i.e. outside forms as ml) is easily mistaken for the digit
1 or the capital
letter I ("eye")
and should not be used.
|
- millilitre
- milliliter
(US)
|
ml
or
mL
|
Derivative units of the litre may use l (lowercase "el").
|
|
|
Not
gramme
,
kilogramme
|
|
|
Spell out in full.
|
|
t
(
not
mt
,
MT
, or
Mt
)
|
|
pound per square inch
|
psi
|
|
|
|
The qualifier
t
or
troy
must be specified where applicable. Use the qualifier avdp (
avoirdupois
) only where there is risk of confusion with troy ounce, imperial fluid ounce, US fluid ounce, or troy pound; but articles about precious metals, black powder, and gemstones should always specify which type of ounce (avoirdupois or
troy
) is being used, noting that these materials are normally measured in troy ounces and grams.
|
- avoirdupois ounce
- avoirdupois pound
|
- oz
or
oz avdp
- lb
or
lb avdp
|
carat
|
carat
|
Used to express masses of gemstones and pearls.
|
carat or karat
|
k
or
Kt
(
not
kt
or
K
)
|
A measure of purity for gold alloys. (Do not confuse with the unit of mass with the same spelling.)
|
|
|
Do not use
′
(
′
),
″
(
″
), apostrophe
(
'
) or quote
(
"
) for minutes or seconds. See also the hours?minutes?seconds formats for time durations described in the
Unit names and symbols table
.
|
year
|
a
|
Use
a
only with an
SI prefix multiplier
(
a rock formation 540
Ma
old
, not
Life expectancy rose to 60
a
).
|
y
or
yr
|
See
§?Long periods of time
for all affected units.
|
bit
|
bit
(
not
b
or
B
)
|
See also
§?Quantities of bytes and bits
, below.
Do not confuse bit/second or byte/second with
baud (Bd)
.
|
byte
|
B
or
byte
(
not
b
or
o
)
|
bit per second
|
bit/s
(
not
bps
,
b/s
)
|
byte per second
|
B/s
or
byte/s
(
not
Bps
,
bps
,
b/s
)
|
arcminute
|
′
|
Markup:
{{
prime
}}
(
prime?
′
not apostrophe/?single quote
'
).
No space (
47
′
, not
47
′
).
|
arcsecond
|
″
|
Markup:
{{
pprime
}}
(
double prime?″
not double-quote
"
).
No space (
22″
, not
22
″
).
|
degree
|
°
|
Markup: degree ° not
masculine ordinal
º
or
ring
?
.
No space (
23°
, not
23
°
).
|
degree Fahrenheit
|
°F
(
not
F
)
|
Markup: Non-breaking space, followed by °:
12
{{
nbsp
}}
°C
, not
12°C
or
12°
{{
nbsp
}}
C
(
12
°C
, not
12°C
or
12°
C
).
Do not use the
precomposed characters
U+2103
℃
DEGREE CELSIUS
and
U+2109
℉
DEGREE FAHRENHEIT
.
|
degree
Rankine
|
°R
(
not
R
)
|
degree Celsius
(
not
degree centigrade)
|
°C
(
not
C
)
|
kelvin
(
not
degree kelvin)
|
K
(
not
°K
)
|
Use a non-breaking space:
12{{nbsp}}K
(use
the normal Latin letter K
, not
U+212A
?
KELVIN SIGN
). When writing out the unit (not usually necessary), pluralize, e.g.
12 kelvins
(see
Kelvin#Orthography
)
|
|
cal
|
In certain subject areas,
calorie
is conventionally used alone; articles following this practice should specify on first use whether the use refers to the small calorie or to the kilocalorie (large calorie). Providing conversions to
SI
units (usually calories to joules or kilocalories to kilojoules) may also be useful. A kilocalorie (
kcal
) is 1000 calories. A calorie (small calorie) is the amount of energy required to heat 1 gram of water by 1
°C. A kilocalorie is also a kilogram calorie.
|
- kilocalorie
- large calorie
- kilogram calorie
- (
not
Calorie??
can be ambiguous)
|
kcal
|
Quantities of bytes and bits
[
edit
]
In quantities of
bits
and
bytes
, the prefixes
kilo-
(symbol
k
or
K
),
mega-
(
M
),
giga-
(
G
),
tera-
(
T
), etc., are ambiguous in general usage. The meaning may be based on a decimal system (like the standard
SI
prefixes), meaning 10
3
, 10
6
, 10
9
, 10
12
, etc., or it may be based on a binary system, meaning 2
10
, 2
20
, 2
30
, 2
40
, etc. The binary meanings are more commonly used in relation to solid-state memory (such as
RAM
), while the decimal meanings are more common for data transmission rates, disk storage and in theoretical calculations in modern academic textbooks.
Prefixes for decimal and binary multiples
|
|
|
|
Follow these recommendations when using these prefixes in Wikipedia articles:
- Following the SI standard, a lower-case
k
should be used for "kilo-" whenever it means 1000 in computing contexts, whereas a capital
K
should be used instead to indicate the binary prefix for 1024 according to JEDEC. If, under the exceptions detailed further below, the article otherwise uses IEC prefixes for binary units, use
Ki
instead.
- Do not assume that the binary or decimal meaning of prefixes will be obvious to everyone. Explicitly specify the meaning of k and K as well as the primary meaning of M, G, T, etc. in an article (
{{
BDprefix
}}
is a convenient helper). Consistency within each article is desirable, but the need for consistency may be balanced with other considerations.
- The definition most relevant to the article should be chosen as primary for that article, e.g. specify a binary definition in an article on RAM, decimal definition in an article on
hard drives
,
bit rates
, and a binary definition for Windows file sizes, despite files usually being stored on hard drives.
- Where consistency is not possible, specify wherever there is a deviation from the primary definition.
- Disambiguation should be shown in bytes or bits, with clear indication of whether in binary or decimal base. There is no preference in the way to indicate the number of bytes and bits, but the notation style should be consistent within an article. Acceptable examples include:
- A 64
MB (
64
×
1024
2
-byte)
video card and a 100
GB
(100
×
1000
3
-byte)
hard drive
- A 64
MB (
64
×
2
20
-byte)
video card and a 100
GB
(100
×
10
9
-byte)
hard drive
- A 64
MB
(67,108,864-byte)
video card and a 100
GB
(100,000,000,000-byte)
hard drive
- Avoid combinations with inconsistent form such as
A 64
MB
(67,108,864-byte)
video card and a 100
GB
(100
×
1000
3
-byte)
hard drive
. Footnotes, such as those seen in
Power Macintosh 5500
, may be used for disambiguation.
- Unless explicitly stated otherwise, one byte is eight bits (see
Byte §?History
).
Binary prefixes for bytes and bits
[
edit
]
The
IEC prefixes
kibi-
(symbol
Ki
),
mebi-
(
Mi
),
gibi-
(
Gi
), etc., are generally not to be used except:
[r]
- when the majority of cited sources on the article topic use IEC prefixes;
- in a direct quote using the IEC prefixes;
- when explicitly discussing the IEC prefixes; or
- in articles in which both types of prefix are used with neither clearly primary, or in which converting all quantities to one or the other type would be misleading or lose necessary precision, or declaring the actual meaning of a unit on each use would be impractical.
Choice of currency
- In
country-specific articles
, such as
Economy of Australia
, use the currency of the subject country.
- In
non-country-specific articles
, such as
Wealth
, use US dollars (
US$123
on first use, generally
$123
thereafter), euros (
€123
), or pounds sterling (
£123
).
Currency names
- Do not capitalize the names or denominations of currencies, currency subdivisions, coins and banknotes: not
a Five-Dollar bill, four Quarters, and one Penny total six Dollars one Cent
but
a five-dollar bill, four quarters, and one penny total six dollars one cent
.
Exception:
where otherwise required, as at the start of a sentence or in such forms as
Australian dollar
.
- To pluralize
euro
, use the standard English plurals (
ten euros and fifty cents
), not the
invariant plurals used for European Union legislation and banknotes
(
ten euro and fifty cent
). For the adjectival form, use a hyphenated singular (
a two-euro pen and a ten-cent coin
).
- Link the first occurrence of lesser-known currencies (e.g.
Mongolian togrogs
).
Currency symbols
- In general, the first mention of a particular currency should use its full, unambiguous signifier (e.g.
A$
52
), with subsequent references using just the appropriate symbol (e.g.
$88
), unless this would be unclear.
Exceptions:
- In an article referring to multiple currencies represented by the same symbol (e.g. the dollars of the US, Canada, Australia, New Zealand, and other countries??
see
Currency symbols §?dollar variants
) use the full signifier (e.g.
US$
or
A$
, but not e.g.
$US123
or
$123 (US)
) each time, except (possibly) where a particular context makes this both unnecessary and undesirable.
- In articles entirely on US-related topics, all occurrences of the
US dollar
may be shortened (
$34
), unless this would be unclear.
- For currencies that use a unit named the "
pound
":
- Use the
£
symbol (
U+00A3
£
POUND SIGN
) for unambiguous referrals to
sterling
, the United Kingdom's currency. Avoid the
U+20A4
?
LIRA SIGN
.
[s]
- GBP
, sterling's ISO 4217 code, should be used to disambiguate that currency from others. Avoid using
stg.
or
GB£
.
[t]
- For currencies other than sterling, use the symbol or abbreviation conventionally employed for that currency, if any.
- Link the first occurrence of lesser-known currency symbols (e.g.
?
)
- If there is no common English abbreviation or symbol, follow the
ISO 4217
standard.
See also
List of circulating currencies
.
Formatting
- A point (full stop or period,
.
)?? never a comma?? is used as the decimal marker (
$6.57
, not
$6,57
).
- For the grouping of digits (e.g.
£1,234,567
) see
§?Grouping of digits
, above.
- Do not place a currency symbol
after
the accompanying numeric figures (e.g.
123$
,
123£
,
123€
) unless that is the normal convention for that symbol when writing in English:
smaller British coins include 1p, 2p, and 5p denominations
.
- Currency abbreviations preceding a numeric value are
unspaced
if they consist of a nonalphabetic symbol alone (
£123
or
€123
), or end with a nonalphabetic symbol (
R$
123
); but
spaced
(using
{{
nbsp
}}
) if completely alphabetic (
R
?123
or
JOD
?123
).
- Ranges should be expressed giving the currency signifier just once:
$250?300
, not
$250
?
$300
.
- million
and
billion
should be spelled out on first use, and (optionally) abbreviated
M
or
bn
(both unspaced) thereafter:
She received £70 million and her son £10M
;
the school's share was
$250?300?million
, and the charity's $400?450M.
- In general, a currency symbol should be accompanied by a numeric amount e.g. not
He converted his
US$
to
A$
but
He converted his US dollars to Australian dollars
or
He exchanged the
US$100
note for Australian dollars
.
- Exceptions may occur in tables and infoboxes where space is limited e.g.
Currencies accepted:
US$
,
SFr
,
£
,
€
. It may be appropriate to wikilink such uses, or add an explanatory note.
Conversions
- Conversions of
lesser-known currencies
may be provided in terms of more familiar currencies?? such as the US dollar, euro or pound sterling?? using an appropriate rate (which is often
not
the current exchange rate). Conversions should be in parentheses after the original currency, along with the convert-to year; e.g.
the grant in 2001 was 10,000,000
Swedish kronor
($1.4M, €970,000, or £850,000 as of 2009
[update]
)
- For
obsolete currencies
, provide an equivalent (formatted as a conversion) if possible, in the modern replacement currency (e.g. euros for amounts denominated in
francs
), or a US-dollar equivalent where there is no modern equivalent.
- In some cases, it may be appropriate to provide a conversion accounting for inflation or deflation over time.
See
{{
Inflation
}}
and
{{
Inflation-fn
}}
.
- When converting among currencies or inflating/deflating, it is rarely appropriate to give the converted amount to more than three significant figures; typically, only two significant figures are justified:
the grant in 2001 was 10,000,000
Swedish kronor
($1.4M, €970,000, or £850,000)
, not
($1,390,570, €971,673 or £848,646)
- The
Insert
menu below the editing window gives a more complete list of math symbols, and allows symbols to be inserted without the HTML encoding (e.g.
÷
) shown here.
- Spaces are placed to left and right when a symbol is used
with two operands
(
the sum 4 + 5
), but no space is used when
there is one operand
(
the value?+5
).
Exception:
spaces are usually omitted in inline fractions formed with
/
:
3/4
not
3 / 4
.
- The
{{
mvar
}}
(for single-letter variables) and
{{
math
}}
(for more complicated expressions) templates are available to display mathematical formulas in a manner distinct from surrounding text.
- The
{{
nbsp
}}
and
{{
nowrap
}}
templates may be used to prevent awkward linebreaks.
Common mathematical symbols
Symbol name
|
Example
|
Markup
|
Comments
|
Plus /
positive
|
x
+
y
|
{{
math
|
''x''
+
''y''
}}
|
|
+
y
|
{{
math
|
+
''y''
}}
|
Minus /
negative
|
x
?
y
|
{{
math
|
''x''
−
''y''
}}
|
Do not use hyphens (
-
) or dashes (
{{
ndash
}}
or
{{
mdash
}}
).
|
?
y
|
{{
math
|
−
''y''
}}
|
Plus-minus /
minus-plus
|
41.5 ± 0.3
|
41.5
±
0.3
|
|
?(±
a
) = ?
a
|
{{
math
|
1
=
−
(
±
''a''
) =
∓
''a''
}}
|
Multiplication,
dot
|
x
?
y
|
{{
math
|
''x''
⋅
''y''
}}
|
Multiplication
,
cross
|
x
×
y
|
{{
math
|
''x''
×
''y''
}}
|
Do not use the letter
x
to indicate multiplication. However, an
unspaced
x
may be used as a substitute for "by" in common terms such as
4x4
.
|
Division
, obelus
|
x
÷
y
|
{{
math
|
''x''
÷
''y''
}}
|
|
Equal / equals
|
x
=
y
|
{{
math
|
1
=
''x''
=
''y''
}}
or
{{
math
|
''x''
{{
=
}}
''y''
}}
|
Note the use of
1=
or
{{
=
}}
to make the template parameters work correctly
|
Not equal
|
x
≠
y
|
{{
math
|
''x''
≠
''y''
}}
|
|
Approx. equal
|
π
? 3.14
|
{{
math
|
''
π
''
≈
3.14
}}
|
Less than
|
x
<
y
|
{{
math
|
''x''
<
''y''
}}
|
Less or equal
|
x
≤
y
|
{{
math
|
''x''
≤
''y''
}}
|
Greater than
|
x
>
y
|
{{
math
|
''x''
>
''y''
}}
|
Greater or equal
|
x
≥
y
|
{{
math
|
''x''
≥
''y''
}}
|
- For draft guidance on, and examples of, coordinates for linear features, see
Wikipedia:WikiProject Geographical coordinates/Linear
.
- Quick guide
:
To add
44°06′45″N
87°54′47″W
? / ?
44.1124°N 87.9130°W
? /
44.1124; -87.9130
to the top of an article, use either
{{Coord|44.1124|N|87.9130|W|display=title}}
(which does not require minutes or seconds but does require the user to specify north/ south and east/west)
or
{{Coord|44.1124|-87.9130|display=title}}
(in which the north and east are presumed by positive values while the south and west are negative ones).
These coordinates are in
decimal degrees
.
- Degrees, minutes and seconds, when used, must each be separated by a
pipe ("|")
.
- Map datum
must be
WGS84
if possible (except for off-Earth bodies).
- Avoid
excessive precision
(0.0001° is <11 m, 1″ is <31 m).
- Maintain
consistency
of decimal places or minutes/seconds between latitude and longitude.
- Latitude (N/S) must appear before longitude (E/W).
Optional coordinate parameters follow the longitude and are separated by
an underscore ("_")
:
Other optional parameters are separated by
a pipe ("|")
:
- display
|display=inline
(the default) to display in the body of the article only,
|display=title
to display at the top of the article only (in desktop view only; title coordinates do not display in mobile view), or
|display=inline,title
to display in both places.
- name
name=
X
to label the place on maps (default is
PAGENAME
)
Thus:
{{Coord|44.1172|-87.9135|dim:30_region:US-WI_type:event
|display=inline,title|name=accident site}}
Use
|display=title
(or
|display=inline,title
) once per article, for the subject of the article, where appropriate.
Geographical coordinates
on Earth should be entered using a template to standardise the format and to provide a link to maps of the coordinates. As long as the templates are adhered to, a robot performs the functions automatically.
First,
obtain the coordinates
. Avoid
excessive precision
.
The
{{
Coord
}}
template offers users a choice of display format through
user styles
, emits a
Geo microformat
, and is recognised (in the
title
position) by the "nearby" feature of Wikipedia's mobile apps and by external service providers such as Google Maps and Google Earth, and Yahoo. Infoboxes automatically emit
{{
Coord
}}
.
The following formats are available.
- For degrees only (including decimal values):
{{coord|
dd
|
N/S
|
dd
|
E/W
}}
- For degrees/minutes:
{{coord|
dd
|
mm
|
N/S
|
dd
|
mm
|
E/W
}}
- For degrees/minutes/seconds:
{{coord|
dd
|
mm
|
ss
|
N/S
|
dd
|
mm
|
ss
|
E/W
}}
where:
- dd
,
mm
,
ss
are the degrees, minutes and seconds, respectively;
- N/S
is either
N
for northern or
S
for southern
latitudes
;
- E/W
is either
E
for eastern or
W
for western
longitudes
;
- negative values may be used in lieu of
S
and
W
to denote Southern and Western
Hemispheres
For example:
For the city of
Oslo
, located at 59° 54′ 50″ N, 10° 45′ 8″ E:
{{coord|59|54|50|N|10|45|08|E}}
?? which becomes
59°54′50″N
10°45′08″E
? / ?
59.91389°N 10.75222°E
? /
59.91389; 10.75222
For a country, like
Botswana
, with no source on an exact geographic center, less precision is appropriate due to uncertainty:
{{coord|22|S|24|E}}
?? which becomes
22°S
24°E
? / ?
22°S 24°E
? /
-22; 24
Higher levels of precision are obtained by using seconds:
{{coord|33|56|24|N|118|24|00|W}}
?? which becomes
33°56′24″N
118°24′00″W
? / ?
33.94000°N 118.40000°W
? /
33.94000; -118.40000
Coordinates can be entered as decimal values:
{{coord|33.94|S|118.40|W}}
?? which becomes
33°56′S
118°24′W
? / ?
33.94°S 118.40°W
? /
-33.94; -118.40
Increasing or decreasing the number of decimal places controls the precision. Trailing zeros may be added as needed to give both values the same appearance.
Heathrow Airport
,
Amsterdam
,
Jan Mayen
and
Mount Baker
are examples of articles that contain geographical coordinates.
Generally, the larger the object being mapped, the
less precise
the coordinates should be. For example, if just giving the location of a city, precision greater than degrees (°), minutes (′), seconds (″) is not needed, which suffice to locate, for example, the central administrative building. Specific buildings or other objects of similar size would justify precisions down to 10
meters or even one meter in some cases (1″ ~15
m to 30
m, 0.0001° ~5.6
m to 10
m).
The final field, following the E/W, is available for attributes such as
type:
,
region:
, or
scale:
(the codes are documented at
Template:Coord/doc §?Coordinate parameters
)
.
When adding coordinates, please remove the
{{
coord missing
}}
tag from the article, if present (often at the top or bottom).
For more information, see
the geographical coordinates WikiProject
.
Templates other than
{{
coord
}}
should use the following variable names for coordinates:
lat_d
,
lat_m
,
lat_s
,
lat_NS
,
long_d
,
long_m
,
long_s
,
long_EW
.
- ^
See Arbitration Committee statements of principles in cases on style-related edit warring in
June 2005
,
November 2005
, and
February 2006
; and
Wikipedia:General sanctions/Units in the United Kingdom
.
- ^
See also
this July 2022 RfC
.
- ^
a
b
c
For use in tables, infoboxes, references, etc. Only certain citation styles use abbreviated date formats. By default, Wikipedia does not abbreviate dates.
Use a consistent citation style within any one article.
- ^
All-numeric
yyyy
-
mm
-
dd
dates might be assumed to follow the
ISO 8601
standard, which mandates the Gregorian calendar. Also, technically all years must have (only) four digits, but Wikipedia is unlikely to need to format a date beyond the year 9999 anytime soon.
- ^
The
routine linking of dates
is deprecated. This change was made August 24, 2008, on the basis of
this archived discussion
. It was ratified in two December 2008 RfCs:
Wikipedia:Manual of Style/Dates and numbers/Three proposals for change to MOSNUM
and
Wikipedia:Manual of Style/Dates and numbers/Date Linking RFC
.
- ^
For consensus discussion on abbreviated date formats like "Sep 2", see
Wikipedia talk:Manual of Style/Archive 151 §?RFC: Month abbreviations
- ^
These formats cannot, in general, be distinguished on sight, because there are usages in which
03-04-2007
represents March
4, and other usages in which it represents April
3. In contrast, there is no common usage in which
2007-04-03
represents anything other than April
3.
- ^
a
b
Body
in this context means the main prose of the article, as distinguished from reference citations, tabular data, infoboxes, navigation templates, and metadata such as hatnote templates, etc. Other parts of the Manual of Style may use
body
to mean 'the bulk of the article after the lead section', but that is not the meaning here. Wikipedia's article leads are not written in a different prose style from the material following them.
- ^
The calendar practices of
Oxford Dictionary of National Biography
and
Encyclopædia Britannica
can be inferred by looking up the birth and death dates of famous, well-documented individuals.
- ^
A change from a preference for two digits, to a preference for four digits, on the right side of
year?year
ranges was implemented in July 2016 per
this RFC
.
- ^
Some precomposed fractions may not work with screen readers, and not all fractions are available precomposed.
- ^
These three characters are in
ISO/IEC 8859-1
and work in screen readers.
- ^
The number in parentheses in a construction like
1.604(48) × 10
?4
J
is the numerical value of the standard uncertainty referred to the corresponding last digits of the quoted result.
[3]
- ^
The
0x
, but not
0b
, is borrowed from the
C programming language
.
- ^
One such situation is with
Unicode
codepoints, which use
U+
;
U+26A7
, not
0x26A7
.
- ^
If there is disagreement about the primary units used in a UK-related article, discuss the matter on the article talk-page or at
Wikipedia talk:Manual of Style/Dates and numbers
(
WT:MOSNUM
). If consensus cannot be reached, refer to historically stable versions of the article and retain the units used in these as the primary units. Also note the
style guides
of British publications (e.g.
The Times
, under "Metric").
- ^
These definitions are consistent with all units of measure mentioned in the
SI Brochure
[4]
and with all units of measure catalogued in
EU directive 80/181/EEC
.
[5]
- ^
Wikipedia follows common practice regarding
bytes
and other data traditionally quantified using
binary prefixes
(e.g.
mega-
and
kilo-
, meaning 2
20
and 2
10
respectively) and their unit symbols (e.g.
MB
and
KB
) for RAM and
decimal prefixes
for most other uses. Despite the IEC's 1998 international standard creating several new binary prefixes (e.g. mebi-, kibi-, etc.) to distinguish the meaning of the decimal
SI prefixes
(e.g.
mega-
and
kilo-
, meaning 10
6
and 10
3
respectively) from the binary ones, and the subsequent incorporation of these IEC prefixes into the
IEC 80000-13
, consensus on Wikipedia in computing-related contexts favours the retention of the more familiar but ambiguous units
KB
,
MB
,
GB
,
TB
,
PB
,
EB
, etc. over use of unambiguous IEC binary prefixes.
For detailed discussion, see
WT:Manual of Style (dates and numbers)/Archive/Complete rewrite of Units of Measurements (June 2008)
.
- ^
Whether 00A3 is displayed with one or two bars is typeface (font) dependent.
- ^
See also
this February 2023 RfC
.
- ^
Garraty, John A.; Carnes, Mark C., eds. (1999). "Editorial note".
American National Biography
. Oxford University Press. pp.?xxi?xxii.
- ^
Coordinated Universal Time (UTC)
(PDF)
.
Bureau International des Poids et Mesures
. June 2, 2009. p.?3. CCTF/09-32
. Retrieved
October 5,
2022
.
This coordination began on January 1, 1960, and the resulting time scale began to be called informally 'Coordinated Universal Time.'?
- ^
"Fundamental Physical Constants: Standard Uncertainty and Relative Standard Uncertainty"
.
The NIST Reference on Constants, Units, and Uncertainty
. US
National Institute of Standards and Technology
. June 25, 2015
. Retrieved
December 12,
2017
.
- ^
a
b
c
"Chapter 4: Non-SI units that are accepted for use with the SI".
SI Brochure: The International System of Units (SI)
(PDF)
(9th?ed.).
Bureau International des Poids et Mesures
. 2019
. Retrieved
2020-09-24
.
Table 8, p 145, gives additional guidance on non-SI units.
- ^
"Council Directive of 20 December 1979 on the approximation of the laws of the Member States relating to units of measurement"
.
Eur-Lex.Europa.eu
.
European Union
. 2017 [1979]. 80/181/EEC (Document 01980L0181-20090527)
. Retrieved
December 12,
2017
.
- ^
Wilkins, G. A. (1989). "5.14 Time and angle".
IAU Style Manual
(PDF)
.
International Astronomical Union
. p.?S23
. Retrieved
12 December
2017
.
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