Gregorian to tabular Hijri converter
The tabular calendar is a fixed arithmetic rule used for historical dates and software, and it covers years before 1300 AH where Umm al-Qura is not available.
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How to use it
- Enter gregorian date and tabular epoch.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Julian day number JDN = day + ceil(29.5 × (month - 1)) + (year - 1) × 354 + floor((3 + 11 × year) / 30) + 1948439; a year is leap when (14 + 11 × year) mod 30 < 11. The reverse conversion solves the same equation.
Example
Inputs: Gregorian date = 2026-09-30, Tabular epoch = Civil: Friday 16 July 622 (most used). Result: Tabular Hijri date: 17 Rabi al-Thani 1448 AH; Numeric (day/month/year): 17/04/1448; Weekday: Wednesday.
Limits and caveats
- The tabular calendar is an approximation and can differ by one or two days from Umm al-Qura and from sighting.
- Gregorian dates before 1582 are treated as proleptic Gregorian, not Julian.
Questions about this tool
How is the tabular calendar different from Umm al-Qura?
The tabular calendar alternates 30 and 29 day months on a fixed cycle, while Umm al-Qura follows the real moon for Makkah.
Which years are leap years in the cycle?
Each 30-year cycle has 11 leap years of 355 days: years 2, 5, 7, 10, 13, 16, 18, 21, 24, 26 and 29 of the cycle.
What is the civil versus astronomical epoch?
The civil epoch starts Friday 16 July 622 and the astronomical one Thursday 15 July 622, so the astronomical date runs one day ahead.