History and Modern Use of the Persian Calendar in Iran and Afghanistan

A Beginner’s Guide to the Persian Calendar: Conversions and Key Dates

The Persian calendar (also called the Solar Hijri or Iranian calendar) is a solar calendar used primarily in Iran and Afghanistan. It’s highly accurate for marking seasons because it’s based on the precise timing of the vernal equinox. This guide explains its structure, common uses, how to convert dates to/from the Gregorian calendar, and key dates to know.

Structure and basics

• Year start: Nowruz (the Persian New Year) — the moment of the vernal equinox (first day of spring). The exact start time varies by year and location but is observed nationwide in Iran.
• Year numbering: Years are counted from the Hijra (the migration of Prophet Muhammad from Mecca to Medina, 622 CE), similar to the Islamic lunar calendar’s epoch, but the Solar Hijri counts solar years.
• Months and lengths: Twelve months; the first six months (Farvardin–Shahrivar) have 31 days each, the next five (Mehr–Bahman) have 30 days each, and the last month (Esfand) has 29 days in common years and 30 days in leap years.
  • 1 Farvardin (فروردین) — 31 days
  • 2 Ordibehesht (اردیبهشت) — 31 days
  • 3 Khordad (خرداد) — 31 days
  • 4 Tir (تیر) — 31 days
  • 5 Mordad (مرداد) — 31 days
  • 6 Shahrivar (شهریور) — 31 days
  • 7 Mehr (مهر) — 30 days
  • 8 Aban (آبان) — 30 days
  • 9 Azar (آذر) — 30 days
  • 10 Dey (دی) — 30 days
  • 11 Bahman (بهمن) — 30 days
  • 12 Esfand (اسفند) — ⁄₃₀ days

Leap years

Leap years follow a complex 33- or 29-year pattern approximating the tropical year; modern Iranian practice determines leap years astronomically (based on precise equinox calculations), which keeps the calendar extremely accurate. In practice, Esfand has 30 days in leap years.

Converting between Persian and Gregorian dates (practical approach)

• Quick mental rule (approximate): Persian year = Gregorian year − 621 for dates between 1 Farvardin and 31 December, and = Gregorian year − 622 for Gregorian dates from 1 January until the day before Nowruz. This is approximate because Nowruz falls around March 20–21.
• Accurate conversion: Use:
  1. A reliable algorithm (e.g., the Jalali algorithm / Khayam algorithm) implemented in libraries (Python’s convertdate, JavaScript libraries like iranian-calendar) or
  2. Reputable online converters that compute the exact moment of Nowruz for the target year.
• Example conversion (simple): Nowruz 1400 SH corresponds to 21 March 2021 (Gregorian). Therefore:
  • 1 Farvardin 1400 = 21 March 2021
  • 10 Mehr 1400 = 2 October 2021 Note: exact mapping for dates near March can shift by a day depending on the equinox time and timezone.

Key dates and observances

• Nowruz (1 Farvardin): Persian New Year, celebrates the vernal equinox — major national holiday.
• Sizdah Bedar (13 Farvardin): Outdoor picnic day; people spend the day outside to avoid bad luck associated with the number 13.
• Mehregan (Mehr, exact day varies by tradition): Ancient festival honoring friendship and love, historically around early October.
• Yalda Night (Shab-e Yalda, 30 Azar): Winter solstice celebration — longest night of the year.
• Islamic holidays: Islamic lunar-calendar holidays (Eid al-Fitr, Eid al-Adha, Ashura, etc.) are observed according to the Islamic calendar; their Persian-calendar dates shift each year.

Practical tips

• Use established libraries or reputable online converters for precise work (legal, historical, scheduling).
• For everyday use, remember Nowruz falls around March 20–21; the Persian year starts then.
• When communicating dates internationally, include both Persian and Gregorian dates to avoid confusion.
• If programming, prefer libraries that implement the Jalali calendar and consider timezone effects on Nowruz.

Quick reference table

Further reading and tools

• Look up implementations named “Jalali” or “Khayam” algorithm for code references.
• Search for language-specific libraries: Python convertdate, JavaScript iranian-date, or trusted online converters.

If you want, I can convert specific dates for you or provide code examples in Python or JavaScript.