As of Version 10.0, calendar functionality is built into the Wolfram Language


converts the date {year,month,day} given in calendar calendar1 into a date given in calendar calendar2.


converts the given date {year,month,day,hour,minute,second}.


  • To use CalendarChange, you first need to load the Calendar Package using Needs["Calendar`"].
  • The following settings can be given for calendar1 and calendar2:
  • GregorianGregorian calendar
    JulianJulian calendar
    IslamicIslamic calendar
    JewishJewish calendar


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Basic Examples  (8)

The Western calendar in current use is the Gregorian calendar. To convert a contemporary Western date to another calendar, use Gregorian for the contemporary Western date.

Israel obtained its independence on May 14, 1948. This finds the Jewish date:

Because the Jewish calendar has a leap month preceding Passover, the Wolfram Language uses a numbering starting with Nisan, the month of Passover:

Israel's independence was declared on the 5th of Iyar, 5708.

This finds the Western date corresponding to the 50th Jewish anniversary:

Between 1582 and 1752, Catholic countries used the Gregorian calendar, while Britain and her colonies used the Julian calendar. To convert British and Catholic dates occurring between 1582 and 1752, it is necessary to change calendars from Julian to Gregorian.

George Washington was born February 22nd, 1732. In France, the date was:

Voltaire was born on November 21st, 1694. In Great Britain the date was:

The Russian Orthodox Church still uses the Julian calendar. This finds the Western (Gregorian) date of Greek Orthodox Christmas 2000:

You can find Islamic dates corresponding to Western (Gregorian) dates:

The Islamic calendar has the following months:

The above date is, therefore, the 24th of Ramadan, 1420.

The Western date for the beginning of Ramadan of the Islamic year 1420:

Hours, minutes, and seconds are left unchanged by CalendarChange:

Possible Issues  (1)

Because it is a solar and lunar calendar (the year follows the seasons, and the months keep track of the phases of the moon), the Jewish calendar has an extra leap month 7 times every 19 years. This leap month occurs in spring the month preceding Passover, so it is appropriate to count the Jewish months starting with Nisan, the month of Passover, as follows:

Since the Jewish year begins in the fall, this numeration of months will not always follow an increasing order; that is, later dates in the same year may have a smaller number for the month: