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LeapYearQ
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LeapYearQ

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LeapYearQ[date]

returns True if the year corresponding to date is a leap year.

Details and Options

  • The date can be specified in the following forms:
  • DateObject[…]date object
    {y,m,d}year, month, day
    {y,m}the first day of the specified month
    {y}the first day of the first month of the year y
    "string"date as a string ("Jan. 1, 2000")
    numberAbsoluteTime specification
  • The following options can be given:
  • CalendarType "Gregorian"calendar in which the date parameters have been specified

Examples

open allclose all

Basic Examples  (4)Summary of the most common use cases

Find whether a date is in a leap year:

In[1]:=1
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https://wolfram.com/xid/0g7jns690oz-c3jhzk
Out[1]=1

Use a compact DateList:

In[1]:=1
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https://wolfram.com/xid/0g7jns690oz-g73n0i
Out[1]=1

An AbsoluteTime specification is allowed:

In[1]:=1
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https://wolfram.com/xid/0g7jns690oz-558ik
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0g7jns690oz-mxobow
Out[2]=2

Use a string specification:

In[1]:=1
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https://wolfram.com/xid/0g7jns690oz-y89y0
Out[1]=1

Options  (3)Common values & functionality for each option

CalendarType  (3)

A leap year in the Jewish calendar is defined as a year of 13 months:

In[1]:=1
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https://wolfram.com/xid/0g7jns690oz-gkvabd
Out[1]=1

In the Islamic tabular calendar, leap years are defined as those years that have a 30-day 12th month:

In[1]:=1
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https://wolfram.com/xid/0g7jns690oz-cutd0i
Out[1]=1

In the Julian calendar, every fourth year is a leap year:

In[1]:=1
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https://wolfram.com/xid/0g7jns690oz-dx6nm6
Out[1]=1

Applications  (1)Sample problems that can be solved with this function

Find the periodicity of leap years in different calendars by analyzing a range of 5000 years:

In[1]:=1
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https://wolfram.com/xid/0g7jns690oz-58l59j

In the Julian calendar, every fourth year is a leap year:

In[2]:=2
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https://wolfram.com/xid/0g7jns690oz-0ys9ma
Out[2]=2

There are 97 leap years every 400 years in the Gregorian calendar:

In[3]:=3
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https://wolfram.com/xid/0g7jns690oz-v3jcm9
Out[3]=3

In the Jewish calendar, there are 7 leap years every 19 years:

In[4]:=4
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https://wolfram.com/xid/0g7jns690oz-oge2o6
Out[4]=4

There are 11 leap years in each cycle of 30 years of the tabular Islamic calendar:

In[5]:=5
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https://wolfram.com/xid/0g7jns690oz-8ikhal
Out[5]=5

Possible Issues  (1)Common pitfalls and unexpected behavior

LeapYearQ accepts both DateList and AbsoluteTime specifications, so numeric inputs are treated as a number of seconds since 1900:

In[1]:=1
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https://wolfram.com/xid/0g7jns690oz-jvu090
Out[1]=1

For year specifications, either a DateList or DateObject form should be used:

In[2]:=2
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https://wolfram.com/xid/0g7jns690oz-dpdyh
Out[2]=2
In[3]:=3
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https://wolfram.com/xid/0g7jns690oz-dzhl0u
Out[3]=3
Wolfram Research (2012), LeapYearQ, Wolfram Language function, https://reference.wolfram.com/language/ref/LeapYearQ.html (updated 2014).
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Wolfram Research (2012), LeapYearQ, Wolfram Language function, https://reference.wolfram.com/language/ref/LeapYearQ.html (updated 2014).

Text

Wolfram Research (2012), LeapYearQ, Wolfram Language function, https://reference.wolfram.com/language/ref/LeapYearQ.html (updated 2014).

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Wolfram Research (2012), LeapYearQ, Wolfram Language function, https://reference.wolfram.com/language/ref/LeapYearQ.html (updated 2014).

CMS

Wolfram Language. 2012. "LeapYearQ." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2014. https://reference.wolfram.com/language/ref/LeapYearQ.html.

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Wolfram Language. 2012. "LeapYearQ." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2014. https://reference.wolfram.com/language/ref/LeapYearQ.html.

APA

Wolfram Language. (2012). LeapYearQ. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/LeapYearQ.html

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Wolfram Language. (2012). LeapYearQ. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/LeapYearQ.html

BibTeX

@misc{reference.wolfram_2025_leapyearq, author="Wolfram Research", title="{LeapYearQ}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/LeapYearQ.html}", note=[Accessed: 23-April-2025 ]}

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@misc{reference.wolfram_2025_leapyearq, author="Wolfram Research", title="{LeapYearQ}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/LeapYearQ.html}", note=[Accessed: 23-April-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_leapyearq, organization={Wolfram Research}, title={LeapYearQ}, year={2014}, url={https://reference.wolfram.com/language/ref/LeapYearQ.html}, note=[Accessed: 23-April-2025 ]}

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@online{reference.wolfram_2025_leapyearq, organization={Wolfram Research}, title={LeapYearQ}, year={2014}, url={https://reference.wolfram.com/language/ref/LeapYearQ.html}, note=[Accessed: 23-April-2025 ]}