- The Persian Solar calendar as the main and national calendar,
- The Gregorian calendar for international events,
- The Islamic calendar (Lunar calendar) for Islamic holidays.
Iranian solar calendar which is a direct descendant of the ancient Zoroastrian calendar is based on the immigration of the Prophet Mohammed from Mecca to Medina in AD 622 and this is why it is called Hijri (immigration). The new year (Nowruz) in this calendar is on the first day of spring falling on 21 March according to the Western calendar. Generally, the Iranian Solar Calendar is synced with the earth`s circulation around the sun and seasons changes and this is what “solar” is originated from.