View source for Wikipedia:Date math

'''Date math''' on Wikipedia is done with [[mw:Help:Magic words#Variables|variables]], [[Help:Template|templates]] and the <code>#time</code> [[mw:Help:Extension:ParserFunctions|parser function]].

In articles, it is almost always preferred to specify a specific static date for a statement or event rather than an automatically generated date. [[Wikipedia:As of]] describes how to properly specify such dates.

== Current date and time ==

{| class="wikitable"
! [[Help:Magic words|Built-in variables]]
! Templates based on them
! What you see
! Comments
|-
| <nowiki>{{CURRENTTIMESTAMP}}</nowiki>
|
| {{CURRENTTIMESTAMP}}
|
|-
| rowspan="4" style="vertical-align: top" | <nowiki>{{CURRENTYEAR}}</nowiki>
|
| {{CURRENTYEAR}}
|
|-
| {{tl|UTC}}
| {{UTC}}
| <small>also uses <nowiki>{{CURRENTMONTH}} {{CURRENTDAY2}} {{CURRENTTIME}}</nowiki>
|-
| {{tl|CURRENTDATE}}
| {{CURRENTDATE}}
| <small>also uses <nowiki>{{CURRENTTIME}} {{CURRENTDAYNAME}} {{CURRENTMONTHNAME}} {{CURRENTDAY}}</nowiki>
|-
| {{tl|CURRENTJULIANDAY}}
| {{CURRENTJULIANDAY}}
| current [[Julian day]] <small>also uses <nowiki>{{CURRENTMONTH}} {{CURRENTDAY}} {{CURRENTHOUR}}</nowiki> {{tl|CURRENTMINUTE}} {{tl|CURRENTSECOND}}
|-
| rowspan="2" style="vertical-align: top" | <nowiki>{{CURRENTMONTH}}</nowiki>
|
| {{CURRENTMONTH}}
|
|-
| {{tl|CURRENTMNTH}}
| {{CURRENTMNTH}}
| trims leading zero
|-
| rowspan="4" style="vertical-align: top" | <nowiki>{{CURRENTMONTHNAME}}</nowiki>
|
| {{CURRENTMONTHNAME}}
|
|-
| {{tl|Month+1}}
| {{Month+1}}
|
|-
| {{tl|Month-1}}
| {{Month-1}}
|
|-
| {{tl|Month-2}}
| {{Month-2}}
|
|-
| <nowiki>{{CURRENTDAY}}</nowiki>
|
| {{CURRENTDAY}}
| day of month
|-
| rowspan="4" style="vertical-align: top" | <nowiki>{{CURRENTDOW}}</nowiki>
|
| {{CURRENTDOW}}
| day of week
|-
| <nowiki>{{#time:l|-1 day}}</nowiki>
| {{#time:l|-1 day}}
|
|-
| <nowiki>{{#time:l}}</nowiki>
| {{#time:l}}
|
|-
| <nowiki>{{#time:l|+1 day}}</nowiki>
| {{#time:l|+1 day}}
|
|-
| colspan="4" style="background:#DDDDDD;" | Any variable or template with a resolution of smaller than one day should not be placed in articles. These variables only indicate when the article was parsed and cached; they may lag by many hours or even days compared to the time the page is viewed.
|-
| <nowiki>{{CURRENTTIME}}</nowiki>
|
| {{CURRENTTIME}}
|
|-
| rowspan="3" style="vertical-align: top" | <nowiki>{{CURRENTHOUR}}</nowiki>
|
| {{CURRENTHOUR}}
|
|-
|<nowiki>{{#time:H|+1 hour}}</nowiki>
|{{#time:H|+1 hour}}
|
|-
| {{tl|Current hour}}
| {{Current hour}}
| trims leading zero
|-
| rowspan="3" style="vertical-align: top" | <nowiki>{{#time:i}}</nowiki>
|
| {{#time:i}}
|
|-
| {{tl|CURRENTMINUTE}}
| {{CURRENTMINUTE}}
| 
|-
| {{tl|Current minute}}
| {{Current minute}}
| trims leading zero
|-
| rowspan="2" style="vertical-align: top" | <nowiki>{{#time:s}}</nowiki>
|
| {{#time:s}}
|
|-
| {{tl|CURRENTSECOND}}
| {{CURRENTSECOND}}
|
|}

== Computed date and time ==

{| class="wikitable"
! Template name
! Usage
! Output
! Comment
|-
| rowspan="2" style="vertical-align: top" | {{tl|Ordinal date}}
| <nowiki>{{Ordinal date|year=2007|month=03|day=15}}</nowiki>
| {{Ordinal date|year=2007|month=03|day=15}}
| returns [[ordinal date]] (day of year)
|-
| <nowiki>{{Ordinal date|year=2008|month=03|day=15}}</nowiki>
| {{Ordinal date|year=2008|month=03|day=15}}
| +1 due to leap year in 2008
|-
| rowspan="2" style="vertical-align: top" | {{tl|WEEKDAY}}
| <nowiki>{{WEEKDAY|2009|08|25}}</nowiki>
| {{WEEKDAY|2009|08|25}}
| returns day of week
|-
| <nowiki>{{WEEKDAYNAME|{{WEEKDAY|2009|08|25}}}}</nowiki>
| {{WEEKDAYNAME|{{WEEKDAY|2009|08|25}}}}
|
|-
| rowspan="3" style="vertical-align: top" | {{tl|JULIANDAY}}
| <nowiki>{{JULIANDAY|2009|08|25}}</nowiki>
| {{JULIANDAY|2009|08|25}}
|
|-
| <nowiki>{{WEEKDAYNAME|{{JULIANDAY|2009|08|25}}}}</nowiki>
| {{WEEKDAYNAME|{{JULIANDAY|2009|08|25}}}}
| Note: 2455069 mod 7 = {{#expr:2455069 mod 7}}
|-
| <nowiki>{{JULIANDAY|{{CURRENTYEAR}}|{{CURRENTMONTH}}|{{CURRENTDAY}}}}</nowiki>
| {{JULIANDAY|{{CURRENTYEAR}}|{{CURRENTMONTH}}|{{CURRENTDAY}}}}
| Nesting templates to get the value of the current Julian day with no decimal portion.  Useful for date math between a set point and the current date.
|-
| rowspan="2" style="vertical-align: top" | {{tl|JULIANDAY.TIMESTAMP}}
| <nowiki>{{JULIANDAY.TIMESTAMP|2455069}}</nowiki>
| {{JULIANDAY.TIMESTAMP|2455069}}
| <small>same format as <nowiki>{{CURRENTTIMESTAMP}}</nowiki>
|-
| {{nowrap|<nowiki>{{#time:D Y-m-d|{{JULIANDAY.TIMESTAMP|2455069}}}}</nowiki>}}
| {{#time:D Y-m-d|{{JULIANDAY.TIMESTAMP|2455069}}}}
| 
|}

Julian dates or day numbers can be used for date calculations. A simple example follows:
# 90 days from 25 December 2006 is: '''{{#time:j F Y|{{JULIANDAY.TIMESTAMP|{{JULIANDAY|2006|12|25}}+90}}}}'''
#* Code: <nowiki>{{#time:j F Y|{{JULIANDAY.TIMESTAMP|{{JULIANDAY|2006|12|25}}+90}}}}</nowiki>
# 90 days from 25 December 2007 is: '''{{#time:j F Y|{{JULIANDAY.TIMESTAMP|{{JULIANDAY|2007|12|25}}+90}}}}''' (1 day less than first example due to leap year in 2008)
#* Code: <nowiki>{{#time:j F Y|{{JULIANDAY.TIMESTAMP|{{JULIANDAY|2007|12|25}}+90}}}}</nowiki>

==Fancy stuff==
{|
| {{today cell}}
| {{tomorrow cell}}
|-
| {{tl|today cell}}
| {{tl|tomorrow cell}}
|}

== See also ==
* [[:Category:Date mathematics templates]]
* [[Help:Variables]]