When you need to go from Hijri to Gregorian
Saudi national IDs, birth certificates, school records, and many government documents are dated in Hijri. International visa applications, foreign universities, airlines, banks, and most non-Saudi systems use Gregorian. Whenever you need to translate a Hijri date for an international form - or check what Gregorian day your Hijri birth date actually was - this converter does the math.
How the conversion works
We convert your Hijri date to a Julian Day Number (JD) - a continuous count of days from a fixed astronomical reference point - using the tabular Islamic calendar algorithm. We then convert that JD into the Gregorian date using Meeus's astronomical algorithm. The day of the week is preserved automatically; converting calendars doesn't change which physical day it actually was.
Tabular Hijri vs Umm al-Qura
Saudi Arabia uses Umm al-Qura - an observation-based calendar where each lunar month begins with a verified new-moon sighting (or an astronomical prediction matching expected sighting). The tabular Islamic calendar used here is a fixed arithmetic approximation that lands within ±1 day. For everyday use the difference is negligible; for legal documents, verify against the official Umm al-Qura source.
Supported date ranges
This converter accepts Hijri years roughly from 1300 (around 1882 CE) to 1500 (around 2076 CE). That window covers every practical use case - birth dates of living people, all current planning, historical research. For dates outside that range the algorithm still works but UX-level validation may flag them.
Why religious dates shift on the Gregorian calendar
Because the Hijri year is ~11 days shorter than the Gregorian year, the same Hijri date falls ~11 days earlier on the Gregorian calendar each year. The 1st of Ramadan, the 1st of Dhu al-Hijjah, and the start of Hajj all drift through the Gregorian seasons over a ~33-year cycle. Use this converter to plan workplace leave or travel around upcoming religious dates.
Precision and the weekday guarantee
Date-to-date precision is ±1 day vs Umm al-Qura. Day-of-the-week is exact - there's no calendar where Tuesday could become Wednesday. We show the weekday on the result so you can spot-verify the conversion against a calendar you already trust.
Frequently asked questions
We use the tabular Islamic calendar - a fixed arithmetic approximation of the Saudi Umm al-Qura observational calendar. The two can differ by up to one day, on dates when the actual new moon sighting and the arithmetic prediction land on different sides of the Hijri month boundary. The Gregorian date will then shift correspondingly. For legal documents, cross-check with the official Umm al-Qura source.
Filling out visa or scholarship forms that demand a Gregorian birth date when your Saudi ID only shows Hijri; planning international travel around upcoming Hijri religious dates (Ramadan, Hajj); verifying contract dates between Saudi and international counterparties.
Yes. The day of the week is a physical fact about the spinning Earth, not a calendar label. Tuesday remains Tuesday regardless of which calendar you use to describe it. We display the day of the week in the result so you can quickly verify against any calendar you already trust.
The Hijri calendar is lunar - based on the 29.53-day cycle of the moon. Twelve lunar months total 354 days in a regular year and 355 in a leap year. The Gregorian calendar is solar - based on Earth's 365.25-day orbit around the Sun. The ~11-day annual gap is why Ramadan moves through the Gregorian seasons over time.
The algorithm works for any date in history. This widget validates Hijri years roughly between 1300 (1882 CE) and 1500 (2076 CE) for UI safety, but the underlying calendar.ts utility can handle anything you ask.
Sources
- Umm al-Qura Calendar (official Saudi calendar)— King Abdulaziz City for Science and Technology (KACST)
- Tabular Islamic Calendar - Astronomical Algorithms (2nd ed.)— Jean Meeus
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