The Umm al-Qura calendar is the official Hijri (Islamic) calendar of Saudi Arabia. Instead of waiting for the moon to be seen, it calculates in advance when each lunar month begins, using sunset and moonset in Makkah. That is why government documents, Iqama records and contracts can carry Hijri dates years ahead. This guide explains how it works, why it sometimes differs from the moon-sighting announcement, and lists every month of 1448 AH.
What is the Umm al-Qura calendar?
The Hijri calendar is lunar: a month begins with the new crescent and lasts 29 or 30 days. Moon sighting, however, varies by place and weather, and a state needs dates it can print years in advance. Umm al-Qura solves this by fixing every month start through calculation, so each Hijri date maps to exactly one Gregorian date.
The name comes from Umm al-Qura (“mother of towns”), a traditional name for Makkah, because the calculation is done for its location.
A short history since 1346 AH
Saudi Arabia began using the Umm al-Qura calendar for administration in 1346 AH (1927). The rule for starting a month changed several times before reaching today’s version. The dates are now calculated at King Abdulaziz City for Science and Technology (KACST) in Riyadh.
| Period | Month-start rule |
|---|---|
| 1346-1369 AH | Actual crescent sighting |
| 1370-1392 AH | Varying calculated rules |
| 1393-1419 AH | New moon before midnight (UT) |
| 1420-1422 AH | Moon sets after the sun in Makkah |
| Since 1423 AH | New moon before sunset and moonset after sunset in Makkah |
How a new month starts in Umm al-Qura
On the evening of the 29th day of a Hijri month, two astronomical conditions are checked for Makkah:
- Conjunction before sunset: the new moon (the moment the moon passes between Earth and Sun) has already happened before sunset that day.
- Moonset after sunset: the moon is still above the horizon after the sun sets, even by a few minutes.
If both are true, the next day is the 1st of the new month and the current month had 29 days. Otherwise the month completes 30 days. The rule does not require the crescent to be visible, only that it is above the horizon.
This is why month lengths follow no fixed pattern. In 1448 AH, Rabi' al-Thani and Jumada al-Ula both have 30 days, back to back.
Umm al-Qura vs moon sighting
Umm al-Qura is a civil calendar. Acts of worship tied to the month, such as fasting Ramadan, Eid al-Fitr and the Day of Arafah, follow the official moon sighting: the Supreme Court calls for sighting on the evening of the 29th and then announces the new month through the Saudi Press Agency.
| Umm al-Qura | Moon sighting | |
|---|---|---|
| Method | Astronomical calculation | Crescent seen after sunset on the 29th |
| Known | Years in advance | On the sighting evening |
| Used for | Documents, contracts, government records | Ramadan, Eid, Hajj |
| Do they differ? | Usually the same; sometimes by one day | |
Example: Umm al-Qura puts 1 Ramadan 1448 on Monday 8 February 2027; the sighting is on the evening of Saturday 6 February. More in Ramadan 2027 in Saudi Arabia.
Months of 1448 AH in the Umm al-Qura calendar
| Month | Starts | Days |
|---|---|---|
| Muharram | Tue 16 June 2026 | 29 |
| Safar | Wed 15 July 2026 | 30 |
| Rabi' al-Awwal | Fri 14 August 2026 | 29 |
| Rabi' al-Thani | Sat 12 September 2026 | 30 |
| Jumada al-Ula | Mon 12 October 2026 | 30 |
| Jumada al-Akhirah | Wed 11 November 2026 | 29 |
| Rajab | Thu 10 December 2026 | 30 |
| Sha'ban | Sat 9 January 2027 | 30 |
| Ramadan | Mon 8 February 2027 | 29 |
| Shawwal | Tue 9 March 2027 | 30 |
| Dhu al-Qa'dah | Thu 8 April 2027 | 29 |
| Dhu al-Hijjah | Fri 7 May 2027 | 30 |
1448 AH has 355 days, and 1449 AH begins on Sunday 6 June 2027. For the meaning of each month name, see Islamic months in order.
Why it matters if you live in Saudi Arabia
Many official records, older documents and some systems still show Hijri dates, while salaries and many government periods use the Gregorian calendar. If a form asks for a Hijri date of birth, or an older document shows a Hijri expiry date, you need the Umm al-Qura equivalent, not an approximate Islamic calendar, or you may be a day off.
How to check any date
Enter it in our Hijri to Gregorian converter, which uses the Umm al-Qura table for 1300 to 1500 AH and shows the weekday and month length. For today’s date with the full month view, open today’s Hijri date. The technical details are on the method page.
Sources
Dates and rules on this page are checked against:
- Official Umm al-Qura Calendar · Kingdom of Saudi ArabiaThe official table of Hijri month starts
- Umm al-Qura Calendar (Arabic) · SaudipediaHistory of the calendar and its month-start rule
- Saudi Arabia's Umm al-Qura calendar · Wikipedia
- The Umm al-Qura Calendar of Saudi Arabia · R. H. van Gent, Utrecht UniversityDetailed study of the calendar rules over time
Frequently asked questions
What is the Umm al-Qura calendar?
It is the official Hijri calendar of Saudi Arabia. Month starts are calculated astronomically for Makkah, and the calendar is used for official documents and transactions.
Is Umm al-Qura based on moon sighting?
No. It is a calculated calendar based on sunset and moonset in Makkah. The start of Ramadan, Shawwal and Dhu al-Hijjah is announced after an actual moon sighting and can differ from the calendar by one day.
Who publishes the Umm al-Qura calendar?
Its dates are calculated at King Abdulaziz City for Science and Technology (KACST) in Riyadh and published on the official Umm al-Qura website and app.
How many days are in an Umm al-Qura month?
Either 29 or 30. There is no fixed pattern, because each month length depends on the timing of the new moon and moonset that month.
Why do Hijri dates differ between websites?
Some sites use an approximate tabular Islamic calendar or another country’s moon sighting, while Umm al-Qura uses the Makkah rule. The result can be a one-day difference.