What's the difference between the Hijri and Gregorian calendars?
The Hijri calendar is a lunar calendar based on the moon's cycle around the Earth, with a year made up of 12 lunar months of 29 or 30 days each — making the Hijri year about 11 days shorter than the Gregorian year. The Gregorian calendar, by contrast, is a solar calendar based on the Earth's orbit around the sun. Because of this gap, the start of each Hijri month gradually shifts through the Gregorian seasons over the years.
Why does the Hijri calendar start from the Prophet's migration?
The Hijri calendar was adopted during the caliphate of Umar ibn al-Khattab, and the migration (Hijra) of the Prophet Muhammad ﷺ from Mecca to Medina was chosen as the starting point of the Islamic era, given the pivotal role this event played in establishing the first Islamic state.
Occasions where you need the Hijri date
- Fasting and holidays: Ramadan, Eid al-Fitr, Eid al-Adha, and the days of Tashreeq.
- Hajj and Umrah: for determining ritual dates and the Hajj season.
- Zakat calculation: since the Zakat year (Hawl) is measured in lunar, not solar, years.
- Contracts and inheritance: some official and religious documents are dated using the Hijri calendar in several Arab countries.
Read also: Hijri vs Gregorian year — how many days is the difference, and why?
Frequently Asked Questions
Is this conversion exactly the same as the official Umm al-Qura calendar?
Yes for current and nearby years: the tool uses the Umm al-Qura tables built into your browser, covering 1300 to 1600 AH; far-off years in them are astronomical calculations, not a published official calendar. Outside that range, or in an old browser without them, it falls back to the arithmetic Hijri calendar, which can differ by a day or two. Some countries rely on moon sighting, so the start of a month there can differ by a day.
How many days are in a Hijri year compared to a Gregorian year?
A lunar Hijri year has 354 or 355 days, while a Gregorian year has 365 or 366 days (in a leap year) — a difference of about 10 or 11 days each year (sometimes 12).
Why does Ramadan shift every year on the Gregorian calendar?
Because the Hijri year is about 11 days shorter than the Gregorian year, Ramadan (and every other Hijri month) moves about 11 days earlier each Gregorian year, cycling through all the seasons over roughly 33 Gregorian years.
Can I see a whole Hijri month?
Open our Hijri calendar, which shows each month with its Hijri and Gregorian days (Umm al-Qura).