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


is an option for calendar functions that specifies which calendar system to use.


  • To use Calendar, you first need to load the Calendar Package using Needs["Calendar`"].
  • Calendar->system specifies to use calendar system system.
  • The following settings can be given:
  • GregorianGregorian calendar
    JulianJulian calendar
    IslamicIslamic calendar
    JewishJewish calendar
  • With Calendar->Automatic, the Julian calendar is used before September 3, 1752, and the Gregorian calendar after September 13, 1752.


Basic Examples  (3)

Compute the number of days in the Islamic year 1420:

Compute the number of days in the Jewish year 5760:

In the Julian calendar, the year 1900 was a leap year:

This is not true in the standard (Gregorian) Western calendar: