Muslims and Arabs live with two calendars simultaneously: the Hijri for religious occasions and official use in many countries, and the Gregorian for international dealings and much of everyday life. Converting between them is a recurring necessity — whether to find your age in Hijri years, determine when a religious event falls, or date an official document. This guide explains the difference between the two calendars and how to convert accurately.
The Hijri calendar is lunar: it is based on the moon's orbit around the Earth. A Hijri year has 12 lunar months and lasts approximately 354 days.
The Gregorian calendar is solar: it is based on the Earth's orbit around the Sun. A Gregorian year lasts approximately 365.25 days.
The difference of about 11 days per year is why Hijri occasions "drift" through the Gregorian seasons — this is why Ramadan falls in summer some years and in winter others.
Because the Hijri year is about 11 days shorter than the Gregorian year, any fixed Hijri date (such as the first of Ramadan) advances approximately 11 days in the Gregorian calendar each year.
Cumulatively: every approximately 33 Gregorian years equal about 34 Hijri years. This is why someone born 33 Gregorian years ago will be approximately a year older in Hijri years.
This difference also explains why your age in Hijri years is greater than your age in Gregorian years — a question many people search for.
Accurate conversion is not simply adding or subtracting a fixed number, because lunar months vary in length (29 or 30 days) and depend on moon-sighting observations.
The official reference in Saudi Arabia is the Umm Al-Qura calendar, which determines the beginning of Hijri months using an approved astronomical calculation method. Reliable calculators rely on it to ensure accuracy.
A quick mental approximation: Gregorian year ≈ Hijri year + 622 − (Hijri year ÷ 33). But for the exact day and month, use a calculator that relies on the Umm Al-Qura calendar.
Example of the divergence: Hijri year 1446 corresponds approximately to Gregorian 2024–2025. The match is not a full year to a full year — each Hijri year spans parts of two Gregorian years.
Official documents: in many Arab countries, national ID cards and official contracts may carry the Hijri date, while international transactions and reservations use the Gregorian date.
Age calculation: many people know their birth date in Hijri and need it in Gregorian (or vice versa) to fill in forms or for retirement calculations.
Religious occasions: determining when Ramadan, Hajj, and the Eids fall in the Gregorian calendar for advance planning (leave, travel, bookings).
Medical and academic appointments: coordinating between institution calendars (which may be Gregorian) and personal Hijri calendars.
A: The Hijri lunar year is about 354 days and the Gregorian solar year is about 365 days — a difference of approximately 11 days per year. This gap is why Hijri occasions drift through the Gregorian seasons.
A: Because the Hijri year is shorter, more Hijri years pass within the same span of time. Every 33 Gregorian years equal roughly 34 Hijri years, so your Hijri age appears about one year older for every 33 years of your life.
A: No. Subtracting or adding a fixed number gives only an approximate year, not the exact day and month. Hijri months vary between 29 and 30 days based on the Umm Al-Qura calendar, so accurate conversion requires a calculator that uses it.
A: It is the official Hijri calendar used in Saudi Arabia, determining the start of lunar months through an astronomical calculation method. Official bodies and reliable calculators rely on it to ensure date accuracy.
A: No. Ramadan advances about 11 days in the Gregorian calendar each year. As a result, it cycles through all seasons over approximately 33 years — falling in summer at times and in winter at others.
A: Use a conversion calculator that relies on the Umm Al-Qura calendar and enter your full Gregorian date (day/month/year) to get the exact Hijri equivalent. A mental estimate is sufficient for the year only, not the day and month.