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The Hijri Calendar Explained

How the Islamic lunar calendar works, why Ramadan moves about 11 days earlier each year, the twelve months, and the difference between calculated and sighted dates.

Updated 27 October 2026 · 4 min read

The Islamic, or Hijri, calendar counts years from the Hijra, the Prophet Muhammad's migration from Makkah to Madinah in 622 CE. Years are written with “AH”, from the Latin anno Hegirae. It sets the dates of Ramadan, both Eids, the Hajj and other observances.

A purely lunar calendar

Each month begins with the new crescent moon and lasts 29 or 30 days. Twelve lunar months make a year of 354 or 355 days, about 11 days shorter than the solar year. Unlike the Jewish or Chinese calendars, the Hijri calendar never adds a leap month to catch up with the seasons.

That is why Ramadan arrives about 11 days earlier each Gregorian year and moves through every season over roughly 33 years. Fasting in midsummer and in midwinter are both part of the cycle.

The twelve months

  1. Muharram: the first month. The 10th is the Day of Ashura.
  2. Safar
  3. Rabi' al-Awwal: many communities mark the Prophet's birth (Mawlid) on the 12th.
  4. Rabi' al-Thani
  5. Jumada al-Ula
  6. Jumada al-Akhirah
  7. Rajab: one of the four sacred months. Isra' and Mi'raj is commonly marked on the 27th.
  8. Sha'ban: the month before Ramadan.
  9. Ramadan: the month of fasting.
  10. Shawwal: begins with Eid al-Fitr.
  11. Dhul-Qa'dah: a sacred month.
  12. Dhul-Hijjah: the month of Hajj. The 9th is the Day of Arafah and the 10th is Eid al-Adha.

Calculated and sighted dates

Because months depend on the crescent being seen, the start of a month can differ by a day between countries, and sometimes between communities in the same city. Some authorities follow astronomical calculation. Saudi Arabia publishes the Umm al-Qura calendar for civil use, while religious months there and elsewhere are confirmed by sighting.

NextSalahClock shows Hijri dates from the Umm al-Qura calendar. Treat them as a reliable guide, but always confirm the start of Ramadan, Eid and Dhul-Hijjah with your local mosque or moon-sighting committee.

See today's Hijri date and the coming year's key dates on the Islamic calendar page, and read the Ramadan timings guide.

Times in this guide are calculated start times. Your mosque may publish different times or iqamah times; see our calculation disclaimer.