The Persian calendar and Nowruz explained

By Omid Jamshidi · Published 20 October 2026 · 6 min read

How the Iranian solar calendar works, how to convert Persian dates in the news into Western dates, and what happens at Nowruz, the Persian New Year celebrated by more than 300 million people.

If you read news from Iran or in Persian, you will soon come across dates such as "28 Mehr 1405". This is not a typing error: Iran uses its own calendar, and its year begins not on 1 January but in spring, with the festival of Nowruz. This guide explains how the calendar works, how to convert its dates and what Nowruz is about.

A solar calendar that starts in spring

Iran's official calendar is the Solar Hijri calendar. Like the Western (Gregorian) calendar, it follows the sun, so its months always fall in the same seasons. It became Iran's official calendar by law in 1925.

Two things make it different:

• The year begins at the spring equinox, around 20 or 21 March. If the equinox happens before noon Tehran time, that day is New Year's Day; otherwise it is the following day. Because the start is fixed by astronomy rather than by a rule of thumb, the calendar matches the seasons very precisely.
• The years are counted from 622 CE, the year the Prophet Muhammad migrated from Mecca to Medina (the Hijra) – but counted in solar years. That is why the Persian year number is about 621 lower than the Western one.

The twelve months

The first six months have 31 days, the next five have 30, and the last has 29 – or 30 in a leap year. In the year 1405, which began on 21 March 2026, the months fall like this (the dates can shift by a day from year to year):

• Farvardin: 21 March – 20 April
• Ordibehesht: 21 April – 21 May
• Khordad: 22 May – 21 June
• Tir: 22 June – 22 July
• Mordad: 23 July – 22 August
• Shahrivar: 23 August – 22 September
• Mehr: 23 September – 22 October
• Aban: 23 October – 21 November
• Azar: 22 November – 21 December
• Dey: 22 December – 20 January
• Bahman: 21 January – 19 February
• Esfand: 20 February – 20 March

The three spring months begin the year, so each season starts at the beginning of a month: summer with Tir, autumn with Mehr – when the school year begins in Iran – and winter with Dey.

How to convert a Persian date

For the year, add 621 to the Persian year for dates from Nowruz to 31 December, and 622 for dates from 1 January to the next Nowruz. For example:

• 28 Mehr 1405 → 1405 + 621 = 2026, and Mehr starts on 23 September, so the 28th is 20 October 2026.
• 10 Dey 1405 → Dey falls partly in January, but the 10th is still in December: 31 December 2026.
• 15 Bahman 1405 → 1405 + 622 = 2027, and Bahman starts on 21 January, so the 15th is 4 February 2027.

For exact conversions, especially near the start of a month, an online date converter is the safest choice. When you compare news across languages, it is worth checking dates carefully: Persian outlets usually give Persian dates, and a report about "last week" may be published days earlier or later in other languages.

Iran also uses a second calendar for religious purposes: the Islamic lunar calendar, whose months follow the moon. Its year is about eleven days shorter, so religious holidays such as Ramadan or Ashura move through the seasons and fall about eleven days earlier in the solar calendar every year.

Nowruz: the Persian New Year

Nowruz means "new day". It marks the first day of spring and is one of the oldest festivals in the world, with roots that reach back thousands of years before Islam. It is celebrated not only in Iran but in Afghanistan, Central Asia, the Caucasus, among Kurds and in diaspora communities worldwide – by more than 300 million people, according to the United Nations. UNESCO added Nowruz to its list of the Intangible Cultural Heritage of Humanity in 2009, and the UN General Assembly declared 21 March the International Day of Nowruz in 2010.

The celebrations stretch over about two weeks:

• Chaharshanbe Suri – on the evening before the last Wednesday of the year, people jump over small bonfires, a custom meant to leave the troubles of the old year behind.
• Haft-sin – families set a table with seven items whose Persian names begin with the letter sin (s), each a symbol of hope: for example sprouted wheat or lentils (sabzeh), a sweet wheat pudding (samanu), dried oleaster fruit (senjed), vinegar (serkeh), apples (sib), garlic (sir) and sumac (somaq). A mirror, candles, painted eggs and goldfish are often added.
• The moment of the new year – families gather at the exact moment of the equinox, called tahvil-e sal, which can fall at any hour of the day or night.
• Visits – the following days are spent visiting relatives, starting with the oldest family members.
• Sizdah Bedar – on the 13th day, people spend the day outdoors, in parks and the countryside, to end the festival. The sprouts from the Haft-sin table are often thrown into running water.

In Iran, the first four days of Farvardin and the 13th are public holidays, and schools close for about two weeks.

Why this matters when you read the news

The calendar affects how events are reported. Iranian budgets, statistics and government plans are usually given for the Persian year, which runs from March to March – so "inflation in 1404" covers a different period than "inflation in 2025". Around Nowruz, public life in Iran slows down for two weeks, which can explain quiet periods in the news. And for millions of people in the diaspora, Nowruz is the most important celebration of the year.

The Persian edition of Omid57.info shows today's date and the publication date of every headline in the Persian calendar, so it is a good place to see the calendar in daily use. Our guide on why the same story looks different in other languages has more tips on dates, numbers and time zones across languages.

Conclusion

The Persian calendar is precise, seasonal and easy to convert once you know its structure: the year starts with spring, the first six months have 31 days, and you add 621 or 622 to the year. And Nowruz, the new day at the spring equinox, is far more than a date – it is a celebration of renewal shared by many peoples and countries.