The short answer
The number of days you have lived is the same on both calendars. What differs is the length of the “year” those days are divided into:
| Calendar | Year length | Mean year |
|---|---|---|
| Gregorian (solar) | 365 or 366 days | 365.2425 days |
| Hijri (lunar) | 354 or 355 days | about 354.37 days |
The gap is about 10.9 days a year; divide the same number of days by a shorter year and you get more years.
How the gap grows
| Gregorian age | Approximate Hijri age | Gap |
|---|---|---|
| 10 years | 10 years 4 months | ~4 months |
| 18 years | 18½ years | ~6 months |
| 33 years | 34 years | ~1 year |
| 50 years | 51½ years | ~1½ years |
| 66 years | 68 years | ~2 years |
A precise example
Born Monday 15 March 1999 (26 Dhu al-Qadah 1419 AH). On 1 January 2026 (12 Rajab 1447 AH):
- Gregorian age: 26 years, 9 months and 17 days.
- Hijri age: 27 years, 7 months and 15 days.
- Days lived: 9,789 on both calendars.
Your Hijri birthday moves
Because the Hijri year is shorter, your Hijri birthday arrives about 11 days earlier each Gregorian year, cycling through all seasons in roughly 33 years. In the example it fell on 13 May 2026 and falls on 3 May 2027. The Age Calculator shows both upcoming birthdays.
Which one is my “real” age?
Both. They are measured in different units, like kilometres and miles. Use the age on whichever calendar the relevant authority uses. If your birth date is recorded in Hijri on an official document, enter it directly in the Hijri Age Calculator. See also How to calculate your Hijri age by hand.
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