How the Hijri calendar works
The Hijri calendar is a lunar calendar of 12 months. Each month begins with the new crescent moon and lasts 29 or 30 days, so a Hijri year has 354 or 355 days. Years are counted from the Hijra, the migration of the Prophet Muhammad from Mecca to Medina in 622 CE, and are marked AH (Anno Hegirae).
The months are Muharram, Safar, Rabiʻ I, Rabiʻ II, Jumada I, Jumada II, Rajab, Shaʻban, Ramadan, Shawwal, Dhuʻl-Qiʻdah and Dhuʻl-Hijjah. Ramadan is the month of fasting; Eid al-Fitr falls on 1 Shawwal, and Eid al-Adha on 10 Dhuʻl-Hijjah.
Why Hijri dates move
Because the Hijri year is about 11 days shorter than the Gregorian year, Hijri dates drift through the seasons. Ramadan moves about 11 days earlier every Gregorian year and completes a full cycle in roughly 33 years.
Calculated calendars and moon sighting
There are two ways to decide when a month begins. Some countries and communities wait for the crescent moon to be seen; others use a calculated calendar. This converter uses Umm al-Qura, the calculated calendar used in Saudi Arabia. Where months start by local sighting, the date can differ by a day.
Birthdays, anniversaries and deadlines
Some families mark birthdays and anniversaries on the Hijri date, and some official documents give expiry dates in the Hijri calendar. Because Hijri dates move about 11 days earlier each Gregorian year, the Gregorian day changes every year. Convert the date for the year ahead, then set a reminder so it does not slip past. For a document with an expiry date, allow for the possibility that the issuing authority counts days slightly differently, and act a few days early.
Examples (Umm al-Qura)
- 1 Ramadan 1447 AH is February 18, 2026.
- 1 Shawwal 1447 AH, Eid al-Fitr, is March 20, 2026.
- October 8, 2026 is 27 Rabiʻ II 1448 AH.
Invited reads documents in 80+ languages and understands 9 calendar systems, including Hijri. Snap an invitation dated in the Hijri calendar and it becomes a reminder in your calendar. Read more in our guide: Hijri calendar explained.