How Many Days Are in a Hijri Year? 354, 355 and Leap Years

A Hijri year (the Islamic lunar year) has 354 or 355 days. It is made of 12 lunar months, and each month has either 29 or 30 days. Twelve average lunar months add up to about 354.37 days, so most years are 354 days long and some get a 355th day to keep the count in step with the moon. That makes the Hijri year about 11 days shorter than the 365- or 366-day Gregorian year. In calendars that set each month by sighting or by astronomical rules, a rare year can come out at 353 or 356 days, as explained below.

Key Takeaways

• A Hijri year has 12 months of 29 or 30 days, which almost always gives 354 or 355 days (rarely 353 or 356 in sighted or rule-based calendars).
• The average lunar month is 29.53059 days, so 12 months average about 354.37 days.
• Tabular (arithmetical) calendars add a leap day in 11 years out of every 30, always at the end of Dhu al-Hijjah.
• Calendars based on sighting or on astronomical rules, such as Umm al-Qura, decide each month separately, so their long years do not follow a fixed pattern.
• By the calculated Umm al-Qura calendar, 1448 AH has 355 days: it runs from 16 June 2026 to 5 June 2027.

Why a Hijri year is 354 or 355 days

The Hijri year is built from moon cycles, not from the sun. The Quran gives the number of months: in Surah at-Tawbah 9:36, a translation of the meaning (Sahih International on quran.com) begins, "Indeed, the number of months with Allāh is twelve [lunar] months."

Each of those months follows one cycle of the moon's phases, from one new crescent to the next. Astronomers call this the synodic month. NASA's eclipse page on the Moon's orbit gives its mean length as 29.53059 days, or 29 days, 12 hours and 44 minutes.

A calendar month cannot contain half a day, so a Hijri month is either 29 or 30 days. In Sahih al-Bukhari 1913, the Prophet ﷺ says the month "is like this and this," which the narration explains as "sometimes of 29 days and sometimes of thirty days." The reasons a given month ends up with 29 or 30 days are covered in why an Islamic month has 29 or 30 days.

The arithmetic follows from there:

• 12 × 29.53059 days = 354.367 days for twelve average lunar months.
• Six 29-day and six 30-day months make 354 days.
• That leaves about 0.367 of a day per year, which adds up to roughly 11 days every 30 years.

So a calendar of plain 354-day years would slowly run ahead of the moon. A 355-day year every two or three years takes up the extra fraction.

The gap with the solar year comes from the same numbers. A Gregorian year averages 365.2425 days, about 10.9 days more than 12 lunar months. The US Naval Observatory's Islamic calendar page rounds this to 11 days. That is why Ramadan and the two Eids move earlier through the seasons, as covered in why Islamic dates move about 11 days earlier each year.

How the tabular calendar handles leap years

The tabular Islamic calendar is a fixed arithmetical scheme. It does not look at the moon at all. Instead it uses a rule that averages out to the right length over time.

Encyclopaedia Britannica's entry on the Islamic calendar describes the classic version. The months alternate between 30 and 29 days, starting with a 30-day Muharram. Only the 12th month, Dhu al-Hijjah, changes length. It has 30 days in 11 years of a 30-year cycle and 29 days in the other 19, "thus, the year has either 354 or 355 days."

The USNO page describes the same structure: a 30-year cycle with 11 leap years, and "an extra day is added to the last month" in each of them.

Which years are leap years?

Historical astronomers did not all pick the same 11 years. R.H. van Gent of Utrecht University lists four intercalation schemes for the tabular calendar. The two most common are:

The only difference is whether the sixth leap year falls in year 15 or year 16 of the cycle. To find a year's place in the cycle, divide the AH year by 30 and take the remainder (a remainder of 0 counts as year 30). For example, 1447 ÷ 30 leaves a remainder of 7, so 1447 AH is a leap year of 355 days under both schemes.

How accurate is the 30-year rule?

It is very close. Eleven leap days per 30 years gives an average year of 354 + 11/30 = 354.3667 days. Twelve mean lunar months come to 354.3671 days. The difference is about 0.0004 days a year, so the tabular calendar drifts by one day against the mean moon only after roughly 2,500 years.

The catch is that real months are not average. NASA notes that the actual length of a lunation "varies from its mean value by up to seven hours." A tabular calendar ignores that, so in any given month it can start a day before or after the crescent is first seen. Our guide to the tabular Islamic calendar goes through the scheme in more detail.

How sighted and calculated calendars differ

Most Muslims do not date religious events by the tabular rule. The USNO page notes that Islamic months traditionally begin "when the thin crescent Moon is actually sighted." In Sahih al-Bukhari 1907, the Prophet ﷺ tells people not to fast until they see the moon, and if the sky is overcast, to complete Sha'ban as thirty days.

In a calendar like this, each month is settled on its own evening. Whether a month has 29 or 30 days depends on the moon's position, the weather and where the observer is. The USNO crescent visibility page explains that the new moon "can be computed exactly," but first sighting of the crescent "cannot be predicted with certainty."

That has two consequences for the year:

• No fixed leap pattern, and not always 354 or 355. A year is 355 days when seven of its months happen to be 30 days long. Which years those are depends on the sky, not on a 30-year table. Nothing in a month-by-month count limits the year to 354 or 355 days, so an occasional year of 353 or 356 days is possible, although uncommon.
• Months do not strictly alternate. Two or more 30-day months can come in a row, and so can two or more 29-day months.

Calculated calendars that follow astronomical rules behave the same way. Van Gent documents the rules of Saudi Arabia's Umm al-Qura calendar. Since 1423 AH, a new month begins after the 29th day only if the geocentric conjunction (new moon) happens before sunset and the moon sets after the sun at Makkah. Otherwise the month runs to 30 days. The year length is simply whatever twelve such months add up to. The calendar's history and purpose are covered in the Umm al-Qura calendar explained.

How a community should start its months, by sighting, by calculation, or by accepting another country's announcement, is a question on which scholars differ. Your local mosque or a qualified scholar is the right place to ask which approach applies to you.

Year lengths for 1444-1452 AH

The table below was computed with the @tabby_ai/hijri-converter package, the converter the site uses, which implements Saudi Arabia's published Umm al-Qura tables for 1343-1500 AH. Each row gives the Gregorian date of 1 Muharram (the Islamic day begins at sunset the evening before) and the number of days until the next 1 Muharram. The last column shows what the Type I and Type II tabular schemes give for the same year. The two schemes agree for every year in this range.

The long years do not line up. In 1445 and 1450 AH the tabular rule adds a day where Umm al-Qura does not, and in 1448 and 1452 AH it is the other way round. Over a full 30-year span the totals stay close: by the converter, 1441-1470 AH contain 12 years of 355 days in the Umm al-Qura calendar, against 11 in the tabular cycle, a difference of a single day over three decades.

The converter also carries Saudi Arabia's older Umm al-Qura record, from before the current rules. A few of those years fall outside 354-355: it gives 353 days for 1401 AH, for example. From 1420 AH onward, every year in the converter's range is 354 or 355 days.

Worked example: the current year, 1448 AH

By the calculated Umm al-Qura calendar, 1448 AH began on 16 June 2026 and 1449 AH begins on 6 June 2027. From 16 June 2026 to 16 June 2027 is 365 days (2027 is not a Gregorian leap year). Subtract the 10 days between 6 June and 16 June, and 1448 AH comes to 355 days.

Here is how those days fall across the months:

Seven months have 30 days, which is what makes this a 355-day year. Notice that Muharram has 29 days here, where the tabular calendar always gives it 30. Rabi al-Thani and Jumada al-Awwal are both 30 days long back to back, and so are Rajab and Sha'ban. A strictly alternating tabular month list could never produce that sequence. Local announcements can still differ from these calculated lengths by a day in any given month.

Common questions

Does the Islamic calendar have leap years?

Tabular Islamic calendars do: 11 years in every 30 get a 355th day at the end of Dhu al-Hijjah. Sighting-based and astronomically calculated calendars have 355-day years too, but they arise from the moon's actual timing rather than a fixed list. No Islamic calendar adds a leap month. The Quran's count of twelve months is the reason, which is explained in why the Islamic calendar has no leap month.

How many weeks are in a Hijri year?

A 354-day year is 50 weeks and 4 days, and a 355-day year is 50 weeks and 5 days. That is why a Hijri date usually falls four or five weekdays later in the following year.

Check the length of any Hijri year

To see a specific year month by month, open the 1448 AH Hijri calendar and count the days in each month, or move to another year from there. To count the days between two dates yourself, convert both with the Hijri date converter and compare the Gregorian results. Both use the calculated Umm al-Qura calendar, so treat the dates for Ramadan, Eid and other observances as planning estimates and confirm them with the authority you follow.