Iran's civil calendar: the Hijri epoch, but solar — so it does not drift.
The Solar Hijri calendar counts from the same event as the lunar Hijri calendar — the migration to Medina — and reckons the year by the sun rather than the moon. Its year begins at the vernal equinox, at Nowruz.
Sharing an epoch with a lunar calendar while running on solar arithmetic produces something that trips up conversion routines: the year numbers are close to the lunar Hijri ones but not equal, and diverge steadily, because a solar year is eleven days longer than a lunar one.
It is the civil calendar of Iran, so Iranian public holidays are fixed in it and converted to Gregorian rather than the other way round.
Both are fixed dates in the Iranian civil calendar, converted to Gregorian — which is why they do not fall on the same Gregorian day each year.
| 🇮🇷 | Thursday 11 February 2027Iran | Victory of the Islamic Revolution22 Bahman in the Solar Hijri calendar. |
| 🇮🇷 | Saturday 20 March 2027Iran | Nationalisation of the Oil Industry29 Esfand, at the end of the Iranian year. |
Same epoch, different arithmetic. The lunar Hijri calendar drifts through the seasons; the Solar Hijri one does not, and their year numbers diverge.
See also hijri calendar · epoch · gregorian calendar
We hold this as rule_type: jalali_date. See what we hold.