Overview of the Solar Hijri Calendar
The Solar Hijri calendar (تقویم هجری شمسی, Taqvīm-e Hejrī-ye Shamsī) is the official calendar of Iran and Afghanistan. Like the Islamic Hijri calendar, it counts years from the Prophet Muhammad's migration (Hijra) in 622 CE — but unlike the Islamic lunar calendar, it is a solar calendar, making it far more accurate for seasonal tracking.
In 2025 CE, the Solar Hijri year is 1403–1404 SH.
The Spring Equinox New Year
The most distinctive feature of the Solar Hijri calendar is that the year begins precisely at the moment of the vernal equinox (the astronomical start of spring). This moment — called Tahvil (تحویل) — is calculated to the second. Nowruz (نوروز, "New Day") is celebrated at this exact astronomical moment, typically around March 20–21.
This makes the Solar Hijri New Year the only major New Year celebration tied to an exact astronomical event rather than a fixed calendar date.
Calendar Structure
The year is divided into 12 months:
- First 6 months: 31 days each (spring and summer)
- Next 5 months: 30 days each (fall and early winter)
- Last month (Esfand): 29 days (30 in a leap year)
The leap year system is more complex than Gregorian: approximately 8 leap years every 33 years, with the exact dates determined by astronomical calculation.
Nowruz — Persian New Year
Nowruz is a 13-day celebration with ancient Zoroastrian roots, predating Islam by millennia. Key traditions include:
- Haft-sin (هفتسین): A ceremonial table with 7 symbolic items beginning with "s" (سین)
- Chaharshanbe Suri: Fire-jumping festival on the last Wednesday before Nowruz
- Sizdah Bedar: 13th day of the new year — picnics outdoors to release bad luck
Nowruz is also celebrated in parts of Central Asia, the Caucasus, South Asia, and by Iranian diaspora worldwide. UNESCO recognized it as an Intangible Cultural Heritage in 2009.
Accuracy
The Solar Hijri calendar is among the most astronomically accurate calendars ever devised. Its error rate is approximately one day per 141,000 years — far more precise than the Gregorian calendar (one day per ~3,030 years).