Persian age: the Solar Hijri (Jalali) calendar

The Solar Hijri calendar is a solar calendar, so an age counted in it comes out to very nearly the same number of years as a Gregorian one. What differs is where the year starts and where the months fall — and the way its leap years are decided, which is by looking at the sky rather than by applying a rule.

The year begins at the equinox

The Gregorian calendar approximates the solar year with a leap rule: three leap years in every four, minus three in every four hundred. It is a very good approximation and it is still an approximation, which is why the equinox wanders across 19, 20 and 21 March.

The Solar Hijri calendar does not approximate. Its year begins on the day the vernal equinox falls, as reckoned on the 52.5°E meridian — the standard meridian of Iran — and it is therefore 365 or 366 days long according to where the equinox lands, with no formula deciding in advance. Leap years come four or five years apart in a pattern that repeats over 33 years, and the pattern is a consequence of the astronomy rather than a rule the calendar is built on.

Nowruz — 1 Farvardin, the first day of the Solar Hijri year — for every year from 1400 to 1425 AP, with the length of the year it begins.
Solar Hijri year	Nowruz falls on	Length of that year
1400 AP	21 March 2021	365 days
1401 AP	21 March 2022	365 days
1402 AP	21 March 2023	365 days
1403 AP	20 March 2024	366 days — a leap year
1404 AP	21 March 2025	365 days
1405 AP	21 March 2026	365 days
1406 AP	21 March 2027	365 days
1407 AP	20 March 2028	365 days
1408 AP	20 March 2029	366 days — a leap year
1409 AP	21 March 2030	365 days
1410 AP	21 March 2031	365 days
1411 AP	20 March 2032	365 days
1412 AP	20 March 2033	366 days — a leap year
1413 AP	21 March 2034	365 days
1414 AP	21 March 2035	365 days
1415 AP	20 March 2036	365 days
1416 AP	20 March 2037	366 days — a leap year
1417 AP	21 March 2038	365 days
1418 AP	21 March 2039	365 days
1419 AP	20 March 2040	365 days
1420 AP	20 March 2041	366 days — a leap year
1421 AP	21 March 2042	365 days
1422 AP	21 March 2043	365 days
1423 AP	20 March 2044	365 days
1424 AP	20 March 2045	366 days — a leap year
1425 AP	21 March 2046	365 days

The twelve months

The first six months have 31 days, the next five have 30, and Esfand has 29 in a common year and 30 in a leap one. That shape follows the seasons: the Earth moves more slowly through its orbit in the northern spring and summer, so those months are genuinely longer.

It also means that a birthday on the 31st of a month is perfectly ordinary in the first half of the year and impossible in the second, which is the kind of detail a calculator that borrows a flat 30 days gets wrong for most of the year.

The months of the Solar Hijri year, with the lengths they take in 1404 AP, a common year.
Month	Persian	Length	Season
1. Farvardin	فروردین	31 days	Spring
2. Ordibehesht	اردیبهشت	31 days	Spring
3. Khordad	خرداد	31 days	Spring
4. Tir	تیر	31 days	Summer
5. Mordad	مرداد	31 days	Summer
6. Shahrivar	شهریور	31 days	Summer
7. Mehr	مهر	30 days	Autumn
8. Aban	آبان	30 days	Autumn
9. Azar	آذر	30 days	Autumn
10. Dey	دی	30 days	Winter
11. Bahman	بهمن	30 days	Winter
12. Esfand	اسفند	29 days (30 in a leap year)	Winter

Where these dates come from

The Solar Hijri (Jalali) calendar as implemented in ICU/CLDR and reached through Intl.DateTimeFormat.

ICU uses the astronomical Solar Hijri calendar, whose year begins at the vernal equinox as observed at the 52.5°E meridian. Far outside the modern era, published tables and arithmetic approximations disagree with it by a day here and there.

There is a second family of Solar Hijri implementations in wide use that decides leap years by arithmetic — a 33-year cycle, in several variants — rather than by computing the equinox. They agree with the astronomical calendar for the years around now and diverge by a day in scattered years further out. Where a date here disagrees with one from another converter, this is the likeliest reason.

Outside 1800–2200 CE this site declines to convert. Prose last reviewed 2026-08-20.

Worked examples

Ages as they stand on 20 August 2026 in Tehran, computed when this page was built. The Gregorian column is alongside for comparison: both calendars are solar, so the two ages agree in years and part company only in the months and days, which are measured against different month boundaries.

Solar Hijri and Gregorian ages on 20 August 2026, Asia/Tehran, for four birthdates.
Birthdate	Solar Hijri birth date	Solar Hijri age	Gregorian age	Next Nowruz
Born 15 May 1990 — an ordinary date in both calendars	25 Ordibehesht 1369 AP (اردیبهشت)	36 y 3 m 4 d	36 y 3 m 5 d	21 March 2027 — 1406 AP begins
Born 20 April 2021 — born on 31 Farvardin, a day no 30-day month has	31 Farvardin 1400 AP (فروردین)	5 y 3 m 29 d	5 y 4 m 0 d	21 March 2027 — 1406 AP begins
Born 21 March 1979 — born on Nowruz	1 Farvardin 1358 AP (فروردین)	47 y 4 m 28 d	47 y 4 m 30 d	21 March 2027 — 1406 AP begins
Born 20 March 2025 — born on 30 Esfand, a date only a leap year has	30 Esfand 1403 AP (اسفند)	1 y 4 m 30 d	1 y 5 m 0 d	21 March 2027 — 1406 AP begins

The era, and the two Hijri calendars

Solar Hijri years are counted AP, anno Persico, from the same event as the Hijri calendar — the migration from Mecca to Medina in 622 CE — but in solar years rather than lunar ones. The two era numbers therefore separate rather than track each other: 1405 AP and 1447 AH are the same stretch of time, and the gap widens by about one year every thirty-three.

The Solar Hijri calendar is the official calendar of Iran, and was for many years the official calendar of Afghanistan. Its month names are Persian and predate Islam; the era is Islamic; the year is astronomical. It is a calendar that is easy to describe wrongly by picking one of those three facts and leaving out the others.