How the Iranian Calendar Works: Months, Leap Years, and Conversions

A Beginner’s Guide to the Iranian Calendar: Festivals, Nowruz, and Timekeeping

Overview

The Iranian calendar (also called the Persian or Solar Hijri calendar) is a solar calendar used officially in Iran and Afghanistan. It aligns closely with the astronomical vernal equinox, making its New Year (Nowruz) fall on the first day of spring. Years are numbered from the Hijra (migration of Muhammad) but follow solar, not lunar, calculations.

Structure

• Months (12): Farvardin (1) through Esfand (12). The first six months have 31 days, the next five have 30 days, and the last month has 29 days (30 in leap years).
• Year start: Begins at the vernal equinox (Nowruz), determined by precise astronomical observation—typically March 20 or 21 in the Gregorian calendar.
• Leap years: Inserted to keep the calendar aligned with the solar year; the pattern is based on precise astronomical rules rather than a simple repeating cycle.

Week and Day Names

• Week has seven days; the workweek commonly runs Saturday–Wednesday with Thursday–Friday as the weekend in Iran.
• Day names are Persian and correspond to planetary/day names historically.

Nowruz (New Year)

• When: Starts at the exact instant of the vernal equinox.
• Significance: Ancient festival over 3,000 years old, celebrated by Iranians and many others across Central and West Asia.
• Customs: House cleaning (khaneh tekani), setting the Haft-Seen table (seven symbolic items), visiting family, and special meals.

Other Major Festivals and Observances

• Sizdah Be-dar (13th day): Outdoor picnic day on the 13th of Farvardin to avoid bad luck.
• Chaharshanbe Suri: Fire-jumping festival on the eve of the last Wednesday before Nowruz.
• Mehregan and Yalda: Ancient seasonal festivals—Mehregan (autumn harvest/thanksgiving), Yalda (winter solstice celebration).
• Islamic religious observances (e.g., Ramadan, Muharram) are observed too, but follow the lunar Islamic calendar for their dates; their occurrence within the Iranian calendar shifts each year.

Converting Dates

• Conversions require accounting for the equinox-based start and leap-year rules. Tools and algorithms exist (e.g., Jalali algorithm) for accurate conversion between Iranian and Gregorian dates.
• Common conversions: Nowruz usually corresponds to March 20 or 21; Esfand 29 (or 30) corresponds to late February/early March.

Practical Tips

• Use reliable libraries or online converters for programming tasks (e.g., language-specific date libraries).
• For legal or official documents in Iran, use the Iranian calendar dates as primary.
• Be aware of regional variants (Iranian vs. Afghan versions differ slightly in naming and leap rules).

Further Reading / Tools

• Search for “Jalali calendar algorithm” or “Iranian calendar converter” for code libraries and online converters.