Hijri ↔ Gregorian Date Converter
Convert between the Islamic (Hijri) and Gregorian calendars — fully offline, no API
Frequently Asked Questions
Converting between the Gregorian and Hijri (Islamic lunar) calendars matters for anyone tracking religious dates — Ramadan, Eid, Hajj — since the Hijri calendar runs on lunar months and drifts against the Gregorian solar calendar by roughly 11 days every year, meaning a fixed Hijri date lands on a different Gregorian date each year.
Why the two calendars drift apart
A Hijri year averages about 354.37 days, against the Gregorian year's roughly 365.25 days — a gap of about 3%, or roughly 11 days per year, that compounds year over year. This is why Ramadan, fixed at the 9th Hijri month, moves earlier through the Gregorian calendar by about 11 days annually rather than falling on the same Gregorian dates each year, cycling through every Gregorian season over roughly a 33-year period. This converter handles both directions — Gregorian-to-Hijri and Hijri-to-Gregorian — and also flags Hijri leap years, since the Islamic calendar has its own leap-year pattern (a 30-year cycle with specific leap years) that's structurally different from the Gregorian four-year leap cycle.
A worked example
The same Gregorian calendar month can fall in different Hijri months across consecutive years — for example, if Ramadan begins in a specific Gregorian month one year, it begins roughly 11 days earlier in the Gregorian calendar the following year, which is exactly why lunar-calendar religious dates can't be reliably predicted from memory of a previous year's Gregorian date.
How this connects to your other Islamic calculations
This converter's underlying calendar logic is what powers the Islamic Age Calculator, since computing Hijri age requires converting a Gregorian birth date into the Hijri calendar first. It's also useful alongside religious-obligation calculators like Zakat and Fitrana, both of which are conventionally calculated and paid around specific Hijri calendar milestones (a full lunar year of wealth-holding for Zakat, before Eid prayer for Fitrana).
Common mistakes
A common mistake is assuming a specific Islamic date will fall in the same Gregorian month every year, based on memory of a previous year — because of the roughly 11-day annual drift, this assumption is wrong more often than it's right, and checking the actual converted date each year (rather than relying on last year's date) avoids miscalculating when a religious observance actually falls.