Understanding the Islamic Calendar
The Islamic calendar is based on a lunar year of 12 full lunar (monthly) cycles, taking 354 days. Each new year in the Islamic calendar thus falls 10 or 11 days earlier according to the 364 day solar calendar. The 12 months of the Islamic year are:
3. Rabi’ al-Awwal (Rabi’ 1)
4. Rabi’ al-Thani (Rabi 2)
5. Jumada al-Ula (Jumada I)
6. Jumada al-Akhirah (Jumada II)
11. Dhu al-Qa’dah
12. Dhi al-Hijjah
The first day of Year One of the Islamic calendar was set as the first day of the Hijrah, the Prophet’s migration from Makkah to Madinah on July 26, 622 C.E. The western convention in designating Islamic dates is thus by the abbreviation AH, which stands for the Latin Anno Hegirae, or ‘Year of the Hijrah’.
To roughly convert an Islamic calendar year (AH) into a Gregorian equivalent (A.D./C.E.), or vice versa, use one of the following equations.
AD = 622 + (32/33 x AH)
AH = 33/32 x (AD – 622)