Building a Persian Calendar in JavaScript: Step-by-Step Guide

Persian Calendar 2026: Important Dates, Holidays, and Conversions

Overview

The Persian calendar (Solar Hijri, or Shamsi) is a solar calendar used in Iran and Afghanistan. It begins each year at the vernal equinox as observed from Tehran (Iran) or Kabul (Afghanistan), producing highly accurate alignment with the seasons. The year 2026 in the Gregorian calendar corresponds to parts of Persian years 1404 and 1405; most of Gregorian 2026 falls in Persian year 1405. Below are key dates, national and religious holidays in Iran, and guidance for converting between Persian and Gregorian dates.

Key Persian months (with approximate Gregorian overlaps)

• Farvardin — starts at the vernal equinox (around March 20–21)
• Ordibehesht — April–May
• Khordad — May–June
• Tir — June–July
• Mordad — July–August
• Shahrivar — August–September
• Mehr — September–October
• Aban — October–November
• Azar — November–December
• Dey — December–January
• Bahman — January–February
• Esfand — February–March

Important Persian dates for 2026 (Gregorian → Persian approximations)

• March 20–21, 2026 — Nowruz (Persian New Year) — start of Farvardin 1, 1405
• March 21, 2026 — Public celebrations and family gatherings (Farvardin 1)
• April 1–3, 2026 — Sizdah Bedar (Nature day; Farvardin 13) — outdoor family picnics
• April 8, 2026 — Islamic holiday observations for Ramadan/Eid depend on lunar sightings; see note below
• September 22–24, 2026 — Mehrgan (traditional festival of autumn/harvest) — roughly Mehr 1 or 2, 1405
• December 31, 2026 — New Year’s Eve (Gregorian) overlaps with Dey/Esfand 1405 depending on year mapping

Note: Some Persian festivals have fixed Solar Hijri dates (Nowruz, Sizdah Bedar, Mehregan), while Islamic religious holidays (e.g., Ramadan, Eid al-Fitr, Eid al-Adha) follow the lunar Islamic calendar and shift relative to Solar Hijri and Gregorian calendars each year.

Official holidays in Iran (typical observances — 2026 specifics may vary)

• Nowruz holidays: Farvardin 1–4 (approximately March 21–24, 2026) — several days off for Nowruz celebrations
• Islamic Republic Day and related state holidays (dates tied to the Solar Hijri calendar, e.g., Ordibehesht/Khordad dates)
• Religious commemorations (e.g., martyrdom and birth anniversaries of Shia Imams) — observed according to the lunar Hijri calendar; exact Gregorian dates vary year to year

For precise 2026 official holiday dates in Iran, consult Iran’s official government calendar or an updated local source, since some observances are set by decree and lunar-based events depend on moon sightings.

Converting Persian and Gregorian dates

• Solar Hijri year starts at the vernal equinox. For most of a Gregorian year 2026, the corresponding Solar Hijri year is 1405 (which begins at Nowruz 2026 ~ March 20–21). Late January–March 20, 2026 correspond to the end of 1404.
• Simple rule-of-thumb:
  • From Farvardin 1 (around March 21) through December 31, add 621 to the Solar Hijri year to get the Gregorian year. Example: 1405 + 621 = 2026 (for dates after Farvardin 1).
  • From January 1 through Esfand 29 (before Farvardin 1), add 622. Example: 1404 + 622 = 2026 (for early 2026 dates before Nowruz).
• Use dedicated conversion libraries for accuracy (they handle leap years and astronomical equinox): examples include:
  • JavaScript: khayyam, moment-jalaali (community libraries)
  • Python: convertdate (module with persian conversion), jdatetime
  • Online converters and authoritative astronomical calculations for exact Nowruz moment

Leap years and accuracy

The Solar Hijri calendar uses an astronomical basis for determining Nowruz (vernal equinox), resulting in a complex leap-year pattern more accurate than the Gregorian average. Leap years are determined by precise astronomical observation or established algorithmic cycles—use tested libraries for programmatic conversion.

Quick conversion examples (approximate)

• Gregorian March 20, 2026 ≈ Esfand 29, 1404 (last day of 1404)
• Gregorian March 21, 2026 ≈ Farvardin 1, 1405 (Nowruz)
• Gregorian June 1, 2026 ≈ Khordad 11 or 12, 1405 (approximate)

Practical tips

• For scheduling across calendars, rely on libraries or official government calendars that account for lunar-based religious holidays and the exact astronomical equinox used locally.
• For coding, prefer well-maintained libraries rather than hand-rolled formulas to avoid subtle leap-year or timezone issues.
• When sharing dates internationally, include both calendars (e.g., “Farvardin 1, 1405 / March 21, 2026”) to avoid confusion.

Resources

• Use reputable conversion libraries (convertdate, jdatetime, khayyam) or national government calendars for definitive holiday listings and legal observances.

If you want, I can produce a printable 2026 Persian-Gregorian date conversion table for key months or generate code examples in JavaScript or Python for accurate conversions.