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.
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.
Can I share or bookmark my calculation?
You can bookmark the calculator page in your browser. Many calculators also display a shareable result summary you can copy. The page URL stays the same so returning to it will bring you back to the same tool.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.
What formula does Hijri Date Converter use?
The formula used is described in the Formula section on this page. It is based on widely accepted standards in the relevant field. If you need a specific reference or citation, the References section provides links to authoritative sources.
Does Hijri Date Converter work offline?
Once the page is loaded, the calculation logic runs entirely in your browser. If you have already opened the page, most calculators will continue to work even if your internet connection is lost, since no server requests are needed for computation.