What Is the Hijri Calendar? A Complete Guide to the Islamic Calendar

The Hijri calendar (also called the Islamic or lunar calendar) is the calendar Muslims use to fix the dates of Ramadan, Hajj, the two Eids and every other religious occasion. It is a purely lunar calendar: each month begins with the new crescent moon, and the year is the sum of twelve such months.

Where the name comes from

"Hijri" refers to the Hijra, the migration of the Prophet Muhammad ﷺ and his companions from Makkah to Madinah in 622 CE. About seventeen years later, during the caliphate of Umar ibn al-Khattab, the Muslim community needed a common way to date letters and documents. The companions chose the year of the Hijra as year 1 and kept Muharram, already the first month of the Arab year, as the start of the year. Years are written with the abbreviation AH, from the Latin Anno Hegirae, "in the year of the Hijra". The first day of the era, 1 Muharram 1 AH, corresponds to 16 July 622 in the Julian calendar.

Twelve lunar months

The Quran states that "the number of months with Allah is twelve" (9:36) and calls the new moons "measurements of time for the people and for Hajj" (2:189). The twelve months are Muharram, Safar, Rabi al-Awwal, Rabi al-Thani, Jumada al-Ula, Jumada al-Akhirah, Rajab, Sha'ban, Ramadan, Shawwal, Dhu al-Qi'dah and Dhu al-Hijjah. Four of them, Muharram, Rajab, Dhu al-Qi'dah and Dhu al-Hijjah, are the sacred months. You can read about each one on our Islamic months page.

The time from one new moon to the next, the synodic month, averages about 29.53 days. A calendar month therefore has either 29 or 30 days, and twelve of them add up to 354 or 355 days, about eleven days shorter than the solar year.

When does a Hijri month begin?

Traditionally a month begins when the thin crescent (hilal) is seen in the western sky just after sunset on the 29th day; if it is not seen, the month is completed to 30 days. Today there are two broad approaches:

• Sighting: the authorities wait for a reliable report of the crescent, locally or from another country.
• Calculation: the start of each month is fixed in advance from astronomical data, as in Saudi Arabia's Umm al-Qura calendar, which HijriTime follows.

Because the two approaches do not always agree, Islamic dates can differ by a day between countries. We explain why in why Islamic dates differ between countries.

The day begins at sunset

In the Islamic calendar a new day starts at Maghrib, not at midnight. That is why Tarawih prayers begin on the night before the first fast of Ramadan, and why "the night of the 27th" falls on the evening of the 26th day.

The Hijri year moves through the seasons

Since the Hijri year is about eleven days shorter than the Gregorian year, every Islamic date arrives about eleven days earlier each year. Ramadan, for example, passes through every season in roughly 33 years. See why Ramadan moves every year.

Using the Hijri calendar today

Saudi Arabia uses the Umm al-Qura calendar for civil purposes, and Muslims everywhere use the Hijri calendar for worship. To see today's date, open the Hijri date today; to convert any date, use the Hijri date converter.