Hijri Date Converter
Calculate hijri date easily with our free tool. Get practical results, tips, and comparisons for everyday decisions. Get results you can export or share.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
JD = floor(365.25 × (Y+4716)) + floor(30.6001 × (M+1)) + D + B − 1524.5 (Gregorian to Julian Day)
The conversion uses Julian Day Numbers as an intermediate step. First, the Gregorian date is converted to a Julian Day Number using the standard astronomical formula. Then, the Julian Day Number is converted to the Hijri calendar using the tabular Islamic calendar algorithm, which accounts for the 30-year leap cycle of the lunar calendar.
Worked Examples
Example 1: Gregorian to Hijri Conversion
Problem:Convert March 21, 2026 (Gregorian) to the Hijri calendar date.
Solution:Using the Julian Day Number algorithm:\n1. Calculate JD for March 21, 2026\n2. Convert JD to Hijri calendar\n3. Result: approximately 1 Ramadan 1447 AH\n(Note: actual date may vary by 1-2 days based on moon sighting)
Result:March 21, 2026 ≈ 1 Ramadan 1447 AH
Example 2: Hijri to Gregorian Conversion
Problem:Convert 10 Dhul Hijjah 1446 AH (Eid al-Adha) to Gregorian.
Solution:Using the reverse Julian Day Number algorithm:\n1. Calculate JD for 10 Dhul Hijjah 1446\n2. Convert JD to Gregorian calendar\n3. Result: approximately June 6, 2025
Result:10 Dhul Hijjah 1446 AH ≈ June 6, 2025
Frequently Asked Questions
Why do Hijri dates sometimes differ between countries?
Hijri dates can differ between countries because the start of each Islamic month traditionally depends on the physical sighting of the new crescent moon (hilal) by reliable witnesses. Since the moon is visible at different times in different locations due to geographical position, weather conditions, and atmospheric clarity, one country may announce the start of a new month a day before or after another. Some countries use astronomical calculations to predict moon visibility, while others rely strictly on physical sighting. Saudi Arabia, for example, uses the Umm al-Qura calendar based on calculations, while many other countries still rely on local moon sighting committees.
How accurate is the mathematical Hijri-Gregorian conversion?
Mathematical conversion algorithms like the Tabular Islamic Calendar provide a systematic approximation but can differ from actual observed dates by one to two days. This is because the actual Islamic calendar is based on moon sighting rather than fixed mathematical rules. The tabular calendar uses an alternating pattern of 29 and 30 day months with a leap day added in specific years of a 30-year cycle (years 2, 5, 7, 10, 13, 16, 18, 21, 24, 26, 29). For historical dates, the margin of error may be larger. For precise religious observances, always refer to your local Islamic authority or mosque for confirmed dates.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy