Iran uses three official calendar systems, including the Solar Hijri calendar as the main and national calendar, the Gregorian calendar for international events and Christian holidays, and the Lunar Hijri calendar for Islamic holidays.
In 2008, the Iranian government's English-language newspaper Iran Daily wrote that "[the] problem of too many annual public holidays has perpetually been a subject of concern," pointing out that the government would often declare "unofficial holidays [...] to allow extended weekends" around the national holidays. "[I]f official and unofficial holidays are added to weekends, almost half the year the country is holidaying! The serious issue of so many holidays should not be tolerated [...]"
Iran is one of the countries with the most public holidays in the world, with 28 holidays. Many holidays' exact dates are determined by the Islamic calendar, and therefore their Gregorian dates vary from year to year.
Al-Quds Day, the last Friday before the end of Ramadan
List of observances set by the Solar Hijri calendar
List of observances set by the Islamic calendar