Hijri Date Converter
Convert a Gregorian date to the Islamic (Hijri) calendar and back, by Saudi Arabia’s Umm al-Qura calendar or the 30-year arithmetic calendar.
Result
Hijri date: 23 Rabi al-Thani 1448 AH
Many communities start Ramadan, Eid and other months on a local sighting of the crescent, which can be a day or two from any calculated calendar.
- Day of the week
- Sunday
https://calcgallery.com/date-time/hijri-date-converter-calculator/
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How to use the Hijri Date Converter
- Choose whether you are converting a Gregorian date to Hijri or a Hijri date to Gregorian.
- Pick the calendar. Umm al-Qura is Saudi Arabia's official calendar; the arithmetic calendar is the rule-based one many books and programs use.
- Enter the date. For a Hijri date, enter the year in AH, pick the month and enter the day.
- Read the converted date and its weekday. If the date is outside the calendar's range, or the month is too short for that day, the page says so instead of guessing.
Two ways to count the Hijri calendar
The Islamic calendar has twelve lunar months and counts years from the Hijra, the emigration from Mecca to Medina in 622. Each month starts with a new crescent moon. People have used two ways to say in advance when that will be.
The arithmetic calendar fixes month lengths by rule. It is exact and goes on forever, so it is the one used for historical dates and in a lot of software. It is not tied to the real moon, so in any given month it can be a day off.
The Umm al-Qura calendar is the one Saudi Arabia publishes for civil use. Each month’s length comes from the moon’s actual position as seen from Mecca, worked out ahead of time. The page reads those lengths from R. H. van Gent’s reconstruction of the calendar, so it only answers for the years that table covers: 1356 to 1500 AH, which is March 1937 to November 2077. Before 1392 AH the table rests on a conversion table published in Saudi Arabia in the early 1990s, and it gives one month, Sha’ban 1364 (July 1945), only 28 days. Other converters built on a computed rule can put month starts before 1420 AH a day or two away from these.
arithmetic month lengths 30, 29, 30, 29, … 30, 29 (30 in a leap year)arithmetic leap years (14 + 11 × year) mod 30 < 11Umm al-Qura month lengths read from van Gent's table, 29 or 30 daysWhat the page does with your date
Each calendar is converted through one running count of days, so a Gregorian date becomes a day number and that day number becomes a Hijri date, or the other way round. The weekday comes from the same count. Nothing is approximated: for the arithmetic calendar the rule is exact, and for Umm al-Qura the table is.
The page won’t answer outside its range. Before 1937 there is no Umm al-Qura table to read, so switch to the arithmetic calendar for older dates. The arithmetic calendar here covers 1583, when the Gregorian calendar began, to the end of 1600 AH.
Months that begin on a sighting
The important dates of the religious year, the start of Ramadan, Eid al-Fitr and Eid al-Adha, are fixed in many places by a sighting of the crescent and not by a printed calendar. A calculated date is the date to plan around, not an announcement. This page cannot know when your community will see the moon.
With your numbers
- Umm al-Qura: each month’s length is the one published for Saudi Arabia, worked out in advance from the moon’s position at Mecca
- A Hijri day begins at sunset, so the evening before the Gregorian date shown already counts as this Hijri date
Quick reference
Many communities start Ramadan, Eid and other months on a local sighting of the crescent, which can be a day or two from any calculated calendar.
| Example | Result |
|---|---|
| 4 October 2026 | Hijri date: 23 Rabi al-Thani 1448 AH |
| 1 January 2027 | Hijri date: 23 Rajab 1448 AH |
| 1 Ramadan 1448 | Gregorian date: February 8, 2027 |
| 1 Shawwal 1448 | Gregorian date: March 9, 2027 |
| 10 Dhu al-Hijjah 1448 | Gregorian date: May 16, 2027 |
| 1 Muharram 1449 | Gregorian date: June 6, 2027 |
| 4 October 2026, arithmetic | Hijri date: 21 Rabi al-Thani 1448 AH |
| 1 Ramadan 1448, arithmetic | Gregorian date: February 8, 2027 |
Where the numbers come from
The fixed figures this calculator relies on, and the published source each one was checked against. How the calculators are built and checked
1 source
R. H. van Gent, "The Umm al-Qura Calendar of Saudi Arabia", Utrecht University, https://webspace.science.uu.nl/~gent0113/islam/ummalqura.htm: the `ummalqura_dat` month starts in https://webspace.science.uu.nl/~gent0113/islam/addfiles/islamcalendar_dat.js, 1 Muharram 1356 AH (14 March 1937) to 1 Muharram 1501 AH (17 November 2077), read by tools/calendar_tables.mjs. All 1,740 month starts in the generated table equal van Gent's (checked 2026-10-13). Before 1392 AH van Gent follows a conversion table published by King Fahd University in the early 1990s, which gives Sha'ban 1364 28 days. The founder chose van Gent over ICU 78.2 `islamic-umalqura` on 2026-10-13: they agree for 1420-1450 AH and differ by -1 to +2 days in 760 months outside it. Spot check: all 13 month starts from Rajab 1447 to Rajab 1448 match https://ummalquracalendar.org/ (read 2026-10-04).
Used for
- Months in the Umm al-Qura table, 1 Muharram 1356 AH (14 March 1937) to the end of 1500 AH (16 November 2077), from van Gent. Verifying this verifies every month length in the table.
Common questions about the Hijri Date Converter
- Why does my mosque or country start Ramadan on a different day?
- Many communities begin a month when the new crescent is actually seen, by eye or by an agreed local method, and announce it the evening before. Any calendar worked out in advance, including both on this page, can then be a day or two away. Treat a converted date for Ramadan, Eid or Dhu al-Hijjah as the expected date, and follow the announcement your community uses.
- What is the Umm al-Qura calendar?
- It is the official civil calendar of Saudi Arabia, computed in advance from the moon's position as seen from Mecca. Its rules have changed several times, most recently from 1423 AH. The page uses the month lengths reconstructed by R. H. van Gent of Utrecht University, which run from 1356 AH (14 March 1937) to 1500 AH (16 November 2077).
- How does the arithmetic Hijri calendar work?
- Months alternate 30 and 29 days, starting with a 30-day Muharram, which gives a 354-day year. In 11 years of every 30 the last month, Dhu al-Hijjah, gains a day, making 355. Those are years 2, 5, 7, 10, 13, 16, 18, 21, 24, 26 and 29 of each cycle. The page counts from the civil epoch, Friday 16 July 622 in the Julian calendar.
- Why do the two calendars sometimes differ by a day or two?
- The arithmetic calendar spreads its long months evenly, while the real moon speeds up and slows down along its orbit. A month that the moon's position makes 29 days long can be 30 days in the arithmetic calendar, so the two drift apart for a few months and then come back together.
- When does a Hijri day begin?
- At sunset. The page labels each Hijri date with the Gregorian day it mostly overlaps, which is how printed calendars do it, so the evening before the Gregorian date shown already belongs to that Hijri date.
- Why is the Hijri year shorter than the Gregorian year?
- Twelve lunar months come to about 354 or 355 days, about 11 days fewer than a solar year. That is why Ramadan comes about 11 days earlier each Gregorian year and passes through every season in about 33 years.