Hijri ↔ Gregorian Date Converter

How it works

Umm al-Qura: look up the Gregorian start of each Hijri month in the official Saudi table (1343–1500 AH), then count days from the month start · Tabular (Kuwaiti): 30-year cycle of 10,631 days with leap years (355 days) in years 2, 5, 7, 10, 13, 16, 18, 21, 24, 26 and 29; months alternate 30 and 29 days (Dhu al-Hijjah has 30 in leap years); JDN = day + ⌈29.5 × (month − 1)⌉ + (year − 1) × 354 + ⌊(3 + 11 × year) ÷ 30⌋ + 1,948,439 · epoch 1 Muharram 1 AH = 16 July 622 (Julian) = JDN 1,948,440 · weekday = (JDN + 1) mod 7, 0 = Sunday

The Islamic calendar is lunar: twelve months of 29 or 30 days, giving a year of 354 or 355 days. That is about eleven days shorter than the Gregorian year, so Ramadan and the Eids arrive roughly eleven days earlier each year and move through all the seasons in about 33 years. Traditionally each month begins when the new crescent is seen, which cannot be known far ahead, so two calendars are used for planning. The Umm al-Qura calendar is the official calendar of Saudi Arabia; its month starts are set in advance from astronomical rules for Mecca and published as a table, which this converter contains for 1343–1500 AH (1924–2077). The tabular calendar, also called the Kuwaiti algorithm, is a simple arithmetic rule with a fixed 30-year leap cycle; it works for any year and usually agrees with Umm al-Qura, but falls one day apart in some months. The converter shows both results side by side, uses the one you pick as the main answer, and switches to the tabular rule outside the Umm al-Qura range. Both directions go through the Julian Day Number, a running count of days, which also gives the weekday. Because Islamic days begin at sunset and local sighting committees may start a month a day early or late, you can shift the result by up to two days.

Worked example

Sunday 18 October 2026 converts to 7 Jumada al-Ula 1448 AH in the Umm al-Qura calendar and 6 Jumada al-Ula 1448 AH in the tabular calendar: one of the months where the two differ by a day. Going the other way, 1 Ramadan 1448 AH falls on Monday 8 February 2027 in both calendars, about eleven days earlier than 1 Ramadan 1447 (Wednesday 18 February 2026). The table of observances then lists the next Islamic New Year, Ashura, Mawlid, Ramadan, Eid al-Fitr, the Day of Arafah and Eid al-Adha with their Gregorian dates and how many days away each one is.

Sources: Umm al-Qura Calendar — official site (King Abdulaziz City for Science and Technology) · hijridate — Umm al-Qura month-start table (open source) · Calendrical Calculations (Reingold & Dershowitz) — arithmetic Islamic calendar

Frequently asked questions