What Is the Hijri Calendar?
The Islamic calendar (التقويم الهجري, at-taqwīm al-hijrī) is a purely lunar calendar consisting of 12 months totaling 354 or 355 days per year — about 11 days shorter than the Gregorian year. Unlike most other lunar calendars, it does not add intercalary months, so Islamic months drift backward through the solar year, completing a full cycle in about 33 years.
The Hijra — Year 1 AH
The calendar begins with the Hijra (هجرة) — the Prophet Muhammad's migration from Mecca to Medina in 622 CE. This event marks year 1 AH (Anno Hegirae). The current Islamic year in 2025 CE is 1446–1447 AH.
The 12 Months
The Islamic year consists of 12 months:
- Muharram, Safar, Rabi' al-Awwal, Rabi' al-Thani
- Jumada al-Ula, Jumada al-Akhirah, Rajab, Sha'ban
- Ramadan (9th) — month of fasting
- Shawwal (Eid al-Fitr on the 1st), Dhu al-Qi'dah, Dhu al-Hijjah (pilgrimage month)
Key Religious Observances
- Ramadan: The 9th month — 29 or 30 days of fasting from dawn to sunset. Because the calendar drifts, Ramadan falls in different Gregorian months each year.
- Eid al-Fitr: Celebration marking the end of Ramadan on the 1st of Shawwal.
- Eid al-Adha: Festival of Sacrifice on the 10th of Dhu al-Hijjah, coinciding with the Hajj pilgrimage.
- Laylat al-Qadr: The Night of Power in the last 10 days of Ramadan.
Moon Sighting vs. Calculation
A practical debate exists in Muslim communities about when a new month begins. Traditional practice requires the physical sighting of the crescent moon by qualified witnesses. Many countries now use astronomical calculation instead, leading to different countries sometimes observing Eid on different days.
The Drifting Calendar
Because the Hijri calendar does not align with seasons, Ramadan can fall in any season. When it falls in summer in the Northern Hemisphere, fasting hours can exceed 18 hours in northern latitudes. When in winter, fasting hours are considerably shorter — illustrating how the purely lunar system interacts with the physical world.