How the Hijri calendar works
The Hijri calendar is a lunar calendar that counts years from the Hijra, the Prophet's migration from Makkah to Madinah in 622 CE. Each month begins with the new crescent moon and lasts 29 or 30 days, so a Hijri year has 354 or 355 days. That is about 11 days shorter than the Gregorian year, which is why Ramadan, Hajj and the Eids move earlier through the seasons by roughly 11 days every year, and why the same Hijri date falls on a different Gregorian date each year.
The Umm al-Qura calendar
There are several ways to fix the Hijri calendar in advance. This converter uses Umm al-Qura, which is calculated from astronomical data for Makkah and is the official calendar of Saudi Arabia for government business, contracts and documents. Most phones, computers and banking apps in the Gulf use it too, so the dates here match what you will see on official Saudi websites and in your phone's Hijri calendar. The converter covers the years 1300 to 1500 AH, which is 1882 to 2077 CE.
Why a date can differ by one day
Religious occasions such as the start of Ramadan, Eid al-Fitr and Eid al-Adha are confirmed by an actual sighting of the crescent moon, announced by the authorities in each country. In some years the moon is sighted a day earlier or later than the calculated calendar expects, and some countries follow their own sighting rather than Saudi Arabia's. So a Hijri date in a country that uses local sighting, or on an old certificate, can be one day different from Umm al-Qura. For legal deadlines, always check the date stated in the official document.
Hijri dates in everyday GCC life
Hijri dates still appear on Saudi government documents, residence and visa records, older ID cards and birth certificates, court papers and some employment contracts, while banks, schools and most businesses use Gregorian dates. Converting between the two is a daily need: matching an expiry date on a document, working out an age or service period, planning around Ramadan and Hajj, or filling in a form that asks for both. Use the numeric day/month/year line when a form needs digits only.
Accurate and private
The conversion runs in your browser using the calendar data built into it, the same data your phone uses, and nothing you enter is sent to our servers. We tested the converter by converting every week from 1990 to 2035 to Hijri and back again and checking each one returned the same day.