Why the two ages differ
A Hijri year follows the moon: twelve lunar months, about 354 days. A Gregorian year follows the sun, about 365. That eleven-day difference means you finish a Hijri year sooner, and the ages pull apart at roughly one extra Hijri year every thirty-three Gregorian ones.
The practical effect is easy to see. Someone in their mid-thirties by the Gregorian calendar is usually a year or so older by the Hijri one; by seventy the gap is closer to two years. Neither figure is more correct than the other — they are answers to two different questions, which is why this page shows both rather than replacing one with the other.
A worked example
Someone born 15 May 1990, checking their age on 23 September 2026, gets a Gregorian age of 36 years, 4 months, 8 days. Their Hijri age, on Umm al-Qura, is 37 years, 5 months, 21 days — over a year higher. 15 May 1990 falls on 20 Shawwal 1410 AH and 23 September 2026 falls on 12 Rabi al-Thani 1448 AH. Hijri years are about 11 days shorter, so more than 37 of them fit into the same stretch of time that has only just passed 36 Gregorian ones.
How it is counted
Not by multiplying. The tempting shortcut — take your normal age and scale it by about 1.03 — gets close and is not right, because the lunar year is not a fixed fraction of a solar one, Hijri months are 29 or 30 days depending on the year, and where your birthday falls in the year changes the answer.
Instead, both dates are converted into the Hijri calendar and the years, months and days between them are counted there directly, in that calendar's own units, borrowing the real length of the previous month when the day of the month has not yet come round. The Gregorian age beside it is counted the same way, so the two are directly comparable rather than one being a duration and the other a count.
Your next Hijri birthday
The result includes the next time the same Hijri day and month come round, as a Gregorian date with a countdown. Because the lunar year is shorter, that date moves about eleven days earlier each year — so a Hijri birthday travels backwards through the Gregorian seasons, completing a full circuit in roughly thirty-three years.
Occasionally there is no answer, and the page says so rather than inventing one. If you were born on day 30 of a month, that day simply does not occur in a year where the month runs to 29 days. Whether such a birthday should be observed on the 29th or on the first of the following month is a question of practice, not arithmetic, and it belongs with a scholar rather than a calculator.
Which Hijri calendar this uses
Umm al-Qura by default — the Saudi civil calendar, which is what most official conversions mean. The two tabular conventions are available if you need them, and the one in use is named in the result.
All three are calculated calendars. The date announced where you live may have been set by a local sighting of the new moon, which can differ by a day and cannot be computed in advance. If your Hijri birth date came from such an announcement, entering it directly on the Hijri setting is more faithful than converting a Gregorian date into it.
Common mistakes
- Multiplying by 1.030684 (365.2425 / 354.367) to approximate a Hijri age. It is close for round numbers but drifts as the birthday's position in the year changes, and it is exactly the shortcut this page avoids by counting real elapsed years and months in the Hijri calendar instead.
- Leaving the calendar picker on the wrong convention for a birth certificate issued under a different one. If a birth date is documented on the tabular calendar rather than Umm al-Qura, switch the picker before comparing figures — Hijri age can differ by up to a year depending on which convention counts the birth month as 29 or 30 days.
- Expecting a next-birthday date for a 30th-day birth every year. Some Hijri years give that month only 29 days, and in those years there is no matching date — see the birthday section above.
Edge cases
A birth date entered as today gives a Hijri and Gregorian age of zero years, zero months, zero days on both sides — there is nothing special-cased about "just born". A birth date in the future is rejected rather than shown as a negative age. Borrowing days from the previous month, used when the day of the month has not yet come round, always uses that month's real length in the calendar chosen, not a flat 30, so the day count stays exact even across the 29/30 split.
Your date of birth stays with you
Everything here runs in your browser. Your birth date is not uploaded, not logged, not stored and not used for anything except the figure on screen — there is no server involved to send it to. Close the tab and nothing of it remains.
Related tools
To convert a single date rather than an age, use the Hijri date converter, which is what this page uses internally and which also shows what the other Hijri conventions say for the same day. For the Solar Hijri calendar used in Iran and Afghanistan, a different calendar despite the shared name, see the Shamsi date converter.