Hijri ↔ Gregorian Date Converter

The Hijri ↔ Gregorian converter uses the Umm al-Qura calendar adopted in Saudi Arabia to translate any date between the two systems instantly. The Hijri calendar follows the lunar year (~354 days) while the Gregorian uses the solar year (~365.25 days), so a drift of ~11 days a year accumulates between them.

How does the Hijri calendar work?

A Hijri year has 12 lunar months totalling 354 or 355 days (a leap year). Umm al-Qura is Saudi Arabia's official calendar; it relies on astronomical calculation reviewed annually by the Council of Ministers. The lunar months in order are: Muharram, Safar, Rabi' al-Awwal, Rabi' al-Thani, Jumada al-Awwal, Jumada al-Thani, Rajab, Sha'ban, Ramadan, Shawwal, Dhu al-Qi'dah, Dhu al-Hijjah.

Conversion algorithm

Conversion is done by translating to the Julian Day Number (JDN) as an intermediate, then from JDN into the target calendar. This achieves ±1 day accuracy versus the printed Umm al-Qura calendar for years after 1937 CE (1356 AH).

Gregorian → JDN → Hijri (and vice versa)

Worked example

Convert 12 May 2026 to Hijri:

1. Input: 2026-05-12 (Tuesday)
2. Bridge through Julian Day Number (JDN)
3. Result: 25 Dhu al-Qi'dah 1447 AH
4. Day: Tuesday

When you need the conversion

• Setting contract and leave dates in the calendar your employer requires.
• Computing the end of a Zakat fiscal year (typically Hijri) from a Gregorian accounting balance.
• Aligning religious milestones (Ramadan, Hajj) with electronic Gregorian calendars.
• Converting a date of birth on a national ID or residency card (sometimes recorded in Hijri, sometimes Gregorian).

Umm al-Qura vs. astronomical calendar

The official Umm al-Qura combines crescent sighting, astronomical calculation, and Council of Ministers decree, so it can differ by ±1 day from the purely astronomical Hijri calendar. Our tool uses the Tabular Islamic algorithm, which matches Umm al-Qura for Gregorian years after 1937 CE. For sensitive official purposes (proof of age, legal contracts), defer to the printed Umm al-Qura calendar.