The Hijri calendar explained simply
How the Islamic calendar works, why dates can differ by a day, and how Gulf official dates are set.
The Hijri calendar is a lunar calendar. Each month begins around the sighting of the new crescent moon, and a year has twelve months of 29 or 30 days, so it is about 354 or 355 days long. The Gregorian calendar used for civil life is roughly 11 days longer each year, which is why Hijri dates move earlier through the seasons.
The twelve months
Muharram, Safar, Rabi al-Awwal, Rabi al-Thani, Jumada al-Awwal, Jumada al-Thani, Rajab, Shaban, Ramadan, Shawwal, Dhu al-Qadah and Dhu al-Hijjah. Ramadan, Eid al-Fitr and Eid al-Adha fall in months 9, 10 and 12.
Why dates can differ by a day
There are two ways to fix the start of a month: by actual moon sighting, or by astronomical calculation. Countries and communities choose differently, and sightings depend on local weather. That means Ramadan or Eid can start on different days in different places, and the day is often confirmed only the evening before.
Saudi Arabia’s Umm al-Qura calendar is a calculation-based system widely used for civil dates. Online converters, including ours, use this type of calendar, so they give a reliable estimate but not a religious ruling. For worship dates such as the start of Ramadan or Eid, follow the announcement from your local religious authority.
Where converted dates are useful
- Reading a Hijri date on a Saudi document or certificate.
- Estimating roughly when an occasion will fall in the Gregorian calendar.
- Working out a Hijri birthday.
Tips
- Treat a converted date as accurate to within a day.
- For official paperwork, use the date printed on the document itself.
- When planning travel around Eid, keep one day of flexibility.
Try the Hijri date converter to move in either direction, and the date calculator to count the days until a date.