How to Convert a Date to the Hijri Calendar and Back

The quickest way to convert a date is our Hijri date converter: today in Pakistan is Rabiʻ II 23, 1448 AH. To do it by hand, use the rule of thumb Hijri year ≈ (Gregorian year − 622) × 33 ÷ 32, and the reverse, Gregorian year ≈ Hijri year × 32 ÷ 33 + 622. For an exact day, you need a calendar table, because Islamic months follow the moon.

Why there is no single exact answer

A Hijri date can differ by a day or more depending on which calendar you follow:

• Umm al-Qura. Saudi Arabia’s official calendar, calculated in advance from astronomical data. Most phone apps and computer systems use it. Today it reads Rabiʻ II 25, 1448 AH.
• Local moon sighting. Pakistan’s dates are set by the Central Ruet-e-Hilal Committee after the crescent is sighted. Today it reads Rabiʻ II 23, 1448 AH, 2 days behind Umm al-Qura.
• Tabular (arithmetical) calendar. A fixed cycle of 30 years, used by historians to convert old dates. It can be a day or two off from either of the others.

So when someone asks “what is the Hijri date of X”, the honest answer includes which calendar you mean. For religious occasions in Pakistan, use the locally announced date.

The year rule of thumb

The Hijri calendar starts in 622 CE, the year of the Hijrah. Since 33 lunar years are almost exactly 32 solar years, you can scale the difference:

Example: for 2026, (2026 − 622) × 33 ÷ 32 = 1,404 × 1.03125 = 1447.9. Today’s Hijri year is 1448. The estimate lands within a year because each Gregorian year overlaps two Hijri years: the new Hijri year begins about 11 days earlier each time.

Reverse: for 1448 AH, 1448 × 32 ÷ 33 + 622 = 2026.1, so 1448 AH falls mostly in 2026 and runs into the next year.

Converting an exact day by hand

You can get within a day or two using the average lengths: a Hijri year averages about 354.37 days and a Hijri month about 29.53 days. The method:

1. Pick a known reference date in both calendars, such as an Eid you remember.
2. Count the days from the reference to your date. Our date duration calculator does this instantly.
3. Divide by 29.53 to get the number of Islamic months, and use the remainder for the day.

Worked example. Pakistan came into being on 14 August 1947. The Umm al-Qura conversion of that day is Ramadan 27, 1366 AH, which is why many people in Pakistan note that independence came on the 27th night of Ramadan. Checking it with the rule of thumb: (1947 − 622) × 33 ÷ 32 = 1366.4, which points to 1366 AH. And since Ramadan is the 9th month, 1,365 full years plus 8 months and 26 days have passed since the start of the calendar.

Converting Hijri to Gregorian

Going the other way works the same: find the Hijri year’s start in the Gregorian calendar, then add the months. Islamic dates move about 11 days earlier each year, so if 1 Ramadan was on a given date this year, next year it will be about 11 days earlier, and the year after about 22 days earlier. For example, Ramadan is expected to begin in Pakistan on Tuesday, February 9, 2027; one year later it will begin roughly 11 days earlier in the calendar. Our guide on why Islamic dates move shows the next several years.

Common mistakes

• Forgetting that the day begins at sunset. An Islamic night such as Shab-e-Barat starts on the evening before its Hijri date in the Gregorian calendar.
• Using a phone app for Pakistani occasions. Most apps follow Umm al-Qura, so they can show Eid a day before Pakistan’s.
• Treating the rule of thumb as exact. It gives the year, not the day.

For birthdays, Islamic anniversaries or historical research, use the converter and check which calendar it uses. To see the full list of months, read the 12 Islamic months.

Frequently asked questions