Lunar Hijri vs Solar Hijri: Two Calendars Called Hijri

The Lunar Hijri calendar is the Islamic calendar of 12 moon-based months, from Muharram to Dhu al-Hijjah, with a year of 354 or 355 days. The Solar Hijri calendar (Hijri Shamsi) is a sun-based calendar of 365 or 366 days. Its year begins at Nowruz, on or just after the March equinox. It is the official calendar of Iran, and Afghanistan's 2004 constitution made it the working calendar of state offices. Both count their years from 622, the year of the Hijra, but they do not run at the same pace.

Take 9 November 2026 as an example: the calculated Lunar Hijri date is 29 Jumada al-Awwal 1448 AH, and the Solar Hijri date is 18 Aban 1405.

Key Takeaways

• Lunar Hijri months follow the moon, so their dates move about 11 days earlier each solar year. Solar Hijri dates stay fixed to the seasons.
• Both calendars count from 622, but the lunar year number is now 42 or 43 higher, and the gap keeps growing.
• Month names are the quickest test: Muharram, Ramadan or Shawwal mean Lunar Hijri; Farvardin, Mehr or Aban mean Solar Hijri (Iran).
• Religious dates such as Ramadan and the two Eids always follow the lunar calendar, even in Iran and Afghanistan.

Both calendars count from the Hijra of 622

Both calendars take the Hijra, the Prophet's ﷺ migration from Makkah to Madinah, as their era. Afghanistan's 2004 constitution, Article 18 put this plainly. It based the country's calendar year on the migration of the Prophet, and it made the solar calendar the basis of work for state offices.

What differs is the unit being counted. The Lunar Hijri calendar counts lunar years of 12 moon cycles. The US Naval Observatory's Islamic calendar page gives its epoch, 1 Muharram AH 1, as Friday 16 July 622 in the Julian calendar. The same page notes that 12 lunar months are on average about 11 days shorter than a civil year. The Quran fixes the number of months at twelve. In the translation of the meaning by Dr. Mustafa Khattab on quran.com, Surah at-Tawbah 9:36 says "the number of months ordained by Allah is twelve."

The Solar Hijri calendar counts tropical years, measured from one March equinox to the next. Astronomer M. Heydari-Malayeri of the Paris Observatory wrote A concise review of the Iranian calendar. He explains that the era starts from the vernal equinox of 622, about six months before the Prophet ﷺ reached Madinah, and that the year begins at Nowruz.

How a Lunar Hijri year and a Solar Hijri year differ

The structural difference is easiest to see side by side.

The month lengths in the Solar Hijri column come from Heydari-Malayeri's review. He gives Iran's months as Farvardin, Ordibehesht, Khordad, Tir, Mordad, Shahrivar, Mehr, Aban, Azar, Dey, Bahman and Esfand. Iran's parliament adopted this form of the calendar on 31 March 1925. That date comes from a study of the 1304/1925 reform in the University of Tehran's Journal for the History of Science.

Where Nowruz falls

The Solar Hijri year starts on the day of the March equinox, judged by Iran time. Heydari-Malayeri describes the rule: if the equinox comes before noon, that day is 1 Farvardin; if it comes after noon, the new year starts the next day.

For 2026, the US Naval Observatory's equinox and solstice data put the March equinox at 14:46 UT on 20 March. Iran Standard Time is UT+3:30, so that was 18:16 in Iran, after noon. Nowruz 1405 therefore fell on 21 March 2026. The 2027 equinox is at 20:25 UT on 20 March (23:55 in Iran). So Nowruz 1406 falls on 21 March 2027, and 1405 is a 365-day year with a 29-day Esfand. In 2029 the equinox comes at 08:02 UT (11:32 in Iran), before noon, so Nowruz falls on 20 March. For the lunar side of year length, see how many days are in a Hijri year.

Why the Lunar Hijri year number is higher

The two calendars started in the same year, but the lunar one counts faster. A solar year is about 11 days longer than a lunar year. So roughly every 33 solar years, the lunar calendar gains a whole extra year. Fourteen centuries of that is why the lunar count (1448) is now ahead of the solar count (1405).

The gap is 42 or 43, depending on the time of year, because the two new years fall at different points. The table shows 2026.

All calculated Lunar Hijri dates in this post come from the Umm al-Qura tables in the open-source hijri-converter library (@tabby_ai/hijri-converter) that this site uses. Local announcements can differ by a day.

The same drift explains why Nowruz lands on a different lunar date every year. Nowruz 1405 (21 March 2026) was 2 Shawwal 1447, calculated. Nowruz 1406 (21 March 2027) is 13 Shawwal 1448, eleven days further into the lunar month. In 2029 it moves into Dhu al-Qi'dah: by the same calculation, Nowruz on 20 March 2029 is 5 Dhu al-Qi'dah 1450. For more on this movement, see why Islamic dates move about 11 days earlier each year.

Solar Hijri 1405 month by month, with Lunar Hijri dates

This table lines up the first day of each Solar Hijri month in 1405 with its Gregorian date. The last column gives the calculated Lunar Hijri date from the same Umm al-Qura tables.

Notice that the lunar date at the start of each solar month moves forward by up to two days, and not at all between some 30-day months. Solar months of 30 or 31 days are on average longer than lunar months, which average about 29.5 days.

How to tell which Hijri calendar a document uses

A date written only as "1405/08/18" or "1448/05/29" can look the same at a glance. These checks settle it in most cases.

1. Read the month name. Muharram, Safar, Rabi al-Awwal, Jumada, Rajab, Sha'ban, Ramadan, Shawwal, Dhu al-Qi'dah and Dhu al-Hijjah are Lunar Hijri. Farvardin through Esfand are Iran's Solar Hijri months. Afghan documents may use a different set of Solar Hijri month names. If a month name is in neither list, check it against an Afghan calendar before converting.
2. Look for the suffix. In Persian and Dari, Solar Hijri dates are marked ه.ش (hijri shamsi) and lunar dates ه.ق (hijri qamari). Arabic documents use هـ for Lunar Hijri. In English you may see SH or AP for Solar Hijri and AH for Lunar Hijri.
3. Compare the year with today. In late 2026, a year near 1405 is almost certainly Solar Hijri, and a year near 1448 is lunar. For older documents, subtract about 621 from the Gregorian year for a Solar Hijri estimate. The lunar year is 42 or 43 higher in 2026, and the gap was smaller in earlier decades.
4. Check the month number against the day. A day of 31 can only be Solar Hijri, in months 1 to 6. Lunar months never have more than 30 days.
5. Consider the source country. Saudi Arabia's calculated calendar is the lunar Umm al-Qura calendar, described by R.H. van Gent of Utrecht University. Iranian civil paperwork uses Solar Hijri dates. Afghan state documents issued under the 2004 constitution used Solar Hijri dates. This post does not cover official practice after the Taliban took control in August 2021, which we could not confirm from a primary source, so check the month name rather than assume.

A worked example

Suppose a document reads "18 Aban 1405". Aban is the eighth Solar Hijri month, so this is Iran's calendar. Farvardin 1 was 21 March 2026. The first six months add up to 186 days and Mehr adds 30, so 1 Aban is day 217 of the year, which is 23 October 2026. 18 Aban is therefore 9 November 2026. On the Lunar Hijri calendar that same day is 29 Jumada al-Awwal 1448 AH, calculated.

Now suppose a document reads "29/05/1448". A year of 1448 and a day of 29 point to Lunar Hijri, and month 5 is Jumada al-Awwal. It is the same day, written in the other calendar.

Which calendar sets Ramadan and Eid?

The Lunar Hijri calendar does, everywhere. Iran's civil life runs on the solar year, yet Ramadan, Eid al-Fitr, the Day of Arafah, Eid al-Adha and Ashura still follow the lunar months there, as they do in Afghanistan. That is why these days fall on a different Solar Hijri date each year, just as they do on the Gregorian calendar.

How a community fixes the first day of a lunar month, by sighting or by calculation, is a separate question on which Muslims differ. The USNO notes that months traditionally begin with the sighting of the crescent after sunset. Van Gent explains that observed dates can differ from the calculated Umm al-Qura dates by a day or more. For the details of the lunar side, see what the Hijri calendar is and how the Islamic year works. For how the year numbers are written, see what AH means. For a personal decision about a religious date, follow your local mosque or a qualified scholar.

Converting a date from either calendar

If you have a Lunar Hijri date, the Hijri date converter gives the Gregorian equivalent from the calculated Umm al-Qura calendar. The Islamic months guide lists the twelve lunar month names in order. For a Solar Hijri date, identify it first with the checks above. Then count from Nowruz (21 March in 2026 and 2027) using the month lengths in the table. Treat any lunar date you get as calculated, and confirm religious dates with your local announcement.