Persian Calendar: A Complete Guide to Dates, Months & Holidays### Overview
The Persian calendar — also called the Iranian calendar, Solar Hijri calendar, or Jalali calendar — is a solar calendar used officially in Iran and Afghanistan. It tracks the tropical year (the cycle of the seasons) and is renowned for its accuracy in aligning the start of each year with the astronomical vernal equinox. The Persian calendar begins its year on Nowruz, the day of the March equinox, which usually falls on March 20 or 21 in the Gregorian calendar.
Historical background
The modern Persian calendar is the product of centuries of astronomical, cultural, and administrative developments:
- Pre-Islamic roots: Ancient Iranian civilizations used various lunisolar and solar systems. The Achaemenid and Sasanian eras influenced later Iranian timekeeping.
- Jalali reform (11th century): A major refinement was implemented under the Seljuk vizier and astronomer Omar Khayyam in 1079 CE (466 AH) during the reign of Sultan Malik Shah. This reform — called the Jalali calendar — dramatically improved accuracy by basing year lengths on astronomical observations and a complex leap year system.
- Adoption of the Solar Hijri: After the Islamic conquest, lunisolar and lunar calendars coexisted. In the 20th century, Iran adopted an improved, more regular version of the Jalali system as the official civil calendar — now commonly called the Solar Hijri or Persian calendar. Afghanistan uses a closely related variant.
Structure and basic rules
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Year numbering: The Persian calendar is a solar calendar whose year count is based on the Hijra (Muhammad’s migration in 622 CE). Years are commonly written as “SH” (Solar Hijri). For example, the Persian year 1404 SH overlapped 2025 in the Gregorian calendar.
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Start of year: Year starts at the vernal equinox (Nowruz) as observed from Tehran (or a specified standard meridian), making the calendar astronomically grounded.
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Months and lengths: The calendar has 12 months:
- Farvardin — 31 days
- Ordibehesht — 31 days
- Khordad — 31 days
- Tir — 31 days
- Mordad — 31 days
- Shahrivar — 31 days
- Mehr — 30 days
- Aban — 30 days
- Azar — 30 days
- Dey — 30 days
- Bahman — 30 days
- Esfand — 29 days (30 in leap years)
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Leap years: The Persian calendar uses a complex leap year system to keep the calendar aligned with the tropical year. Leap years add a day to Esfand (making it 30 days). Modern implementations commonly use an algorithmic 33-year cycle with occasional 29- and 37-year corrections, or they determine leap years astronomically. Leap years occur roughly every 4 years but are adjusted to maintain seasonal alignment.
Months and cultural significance
Each Persian month has cultural, historical, and often Zoroastrian-rooted names:
- Farvardin (فروردین): Associated with guardian spirits (Fravashis) in Zoroastrian tradition; marks the spring beginning.
- Ordibehesht (اردیبهشت): Name linked to Asha Vahishta (truth, order).
- Khordad (خرداد): Associated with completeness and the divine.
- Tir (تیر): Linked to the deity Tishtrya and rainfall.
- Mordad (مرداد): From Amurdad, meaning “immortality.”
- Shahrivar (شهریور): From Kshatra Vairya, meaning “desirable dominion.”
- Mehr (مهر): Means “sun” or “friendship”; linked to Mithra.
- Aban (آبان): Means “waters.”
- Azar (آذر): Means “fire.”
- Dey (دی): Associated with the Creator; mid-winter period.
- Bahman (بهمن): Linked to good purpose and thought.
- Esfand (اسفند): Last month; associated with protection.
These names reflect pre-Islamic Iranian cosmology and religious vocabulary, and they remain in use today in secular and religious cultural contexts.
Nowruz — Persian New Year
Nowruz (meaning “new day”) is the most important holiday in the Persian cultural sphere. It marks the vernal equinox and is celebrated across Iran, Afghanistan, Central Asia, and by diaspora communities worldwide. Traditions include:
- Haft-Seen: A ceremonial table with seven symbolic items beginning with the Persian letter “S” (seen), such as sabzeh (green sprouts), samanu (sweet pudding), seer (garlic), seeb (apple), senjed (oleaster fruit), somaq (sumac), and serkeh (vinegar).
- Spring cleaning (khaneh tekani), visiting family, charity, and special meals.
- Sizdah Bedar: Outdoor picnic day on the 13th day of Farvardin to avoid bad luck.
Nowruz celebrations often last about two weeks and combine ancient Zoroastrian, regional, and Islamic-era customs.
Religious and public holidays tied to the Persian calendar
Because the Persian calendar is solar, many fixed public holidays fall on the same Persian date every year. Important ones include:
- Nowruz (Farvardin 1) — New Year and first day of spring.
- Farvardin 12–13 — Islamic martyrdom commemorations and Sizdah Bedar (April 1–2 in many years).
- Islamic Republic Day (Farvardin 12 in Iran historically observed) and Revolution Day (Bahman 22 — 1979 revolution anniversary).
- National and cultural observances like Teacher’s Day (varies), and anniversary dates of notable events recorded by Persian dates.
Religious holidays based on the Islamic lunar (Hijri) calendar — such as Ramadan, Eid al-Fitr, Eid al-Adha, and Ashura — move through the Persian year because they follow the lunar calendar, so their Persian dates change each solar year.
Converting between Persian and Gregorian calendars
Conversion between Persian and Gregorian dates can be done in several ways:
- Astronomical method: Calculate the exact time of the March equinox for the chosen meridian and base the Persian year start on that moment.
- Algorithmic methods: Several well-established algorithms convert dates reliably (e.g., the Khayyam algorithm or routines used in programming libraries). Many programming languages and libraries provide conversion functions.
- Online converters: Numerous tools do instant conversions; for scripting, libraries exist in Python, JavaScript, and other languages.
Example conceptual rule: Persian year N begins on the Gregorian date of the vernal equinox that falls in Gregorian year G, where N ≈ G − 621 (but exact mapping requires checking equinox timing and leap rules).
Leap-year details (more precise)
The Persian calendar’s leap-year pattern is one reason for its long-term accuracy. While many explanations simplify it as a 33-year cycle with leap years every 4th year except at certain intervals, the precise legal or civil rule varies by implementation:
- Observational approach: Some authorities determine leap years by observing the equinox; if the equinox occurs before noon at the reference meridian, the day is counted as the first day of the new year.
- Algorithmic approach: Civil administrations often use an arithmetic leap-year table that closely matches astronomical results over long periods.
For practical purposes: Esfand has 29 days in common years and 30 days in leap years.
Use today and regional variants
- Iran: Official civil calendar; used for government, business, and everyday life.
- Afghanistan: Uses the Solar Hijri but with slightly different month-name spellings and sometimes different epoch references.
- Diaspora communities: Many ethnic Persians, Kurds, and Tajiks use the Persian calendar culturally.
Programming examples (resources and tips)
Common programming libraries and tools:
- Python: convertdate, khayyam (third-party), or use custom algorithms.
- JavaScript: moment-jalaali (plugin for Moment.js), jalali-moment, or libraries like persian-date.
- Databases: Some localizations support Persian calendar formatting but often require application-level conversion.
Simple conversion pseudo-logic:
1. Compute Julian day number (JDN) for Gregorian date. 2. Use JDN to compute Solar Hijri year start based on March equinox or algorithmic epoch. 3. Calculate Persian month/day by offset from year start. (Use established libraries for production code to avoid subtle leap-year bugs.)
Common questions
- Is the Persian calendar the same as the Islamic calendar? No. The Persian calendar is solar; the Islamic (Hijri) calendar is lunar.
- Does Nowruz change every year? No — Nowruz always falls on the vernal equinox, so its Gregorian date may shift between March 20–21 depending on the year and time zone.
- Why are some Persian years labeled SH (e.g., 1404 SH)? SH stands for Solar Hijri, indicating the solar-based era that begins from the Hijra epoch.
Further reading and references
For in-depth study, consult works on the history of Islamic and Persian astronomy, papers on the Jalali reform, and documentation for conversion libraries and government calendar standards.
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