A calendar built on the moon
The Islamic calendar is lunar: each month begins with the new crescent moon and lasts 29 or 30 days, giving a year of about 354 days. That is roughly eleven days shorter than the 365-day solar (Gregorian) year, which is why Islamic dates move earlier each year relative to the seasons.
Where it starts
The Hijri era is counted from the Hijrah — the Prophet Muhammad's migration from Makkah to Medina in 622 CE. Years are written "AH" (Anno Hegirae). So a Hijri year and a Gregorian year never line up exactly; each Gregorian year overlaps two Hijri years.
The twelve months
- Muharram
- Safar
- Rabi' al-Awwal
- Rabi' al-Thani
- Jumada al-Awwal
- Jumada al-Thani
- Rajab
- Sha'ban
- Ramadan
- Shawwal
- Dhu al-Qa'dah
- Dhu al-Hijjah
Key dates through the year
- 1 Muharram — the Islamic New Year.
- 10 Muharram (Ashura) — a recommended day of fasting.
- Ramadan — the month of fasting, including the Night of Power (Laylat al-Qadr) in its last ten nights.
- 1 Shawwal — Eid al-Fitr, marking the end of Ramadan.
- 8–13 Dhu al-Hijjah — the days of Hajj.
- 9 Dhu al-Hijjah — the Day of Arafah.
- 10 Dhu al-Hijjah — Eid al-Adha.
Why crescent sighting matters
Because a month begins with the new crescent, the exact start of months like Ramadan and Shawwal can depend on whether the moon is sighted — by the naked eye in some traditions, or by calculation in others. This is why Eid can fall on slightly different days in different countries. Both calculated and sighting-based approaches are followed by various communities.
Reading Hijri dates on SalatWaqt
Every page on SalatWaqt shows today's Hijri date beside the Gregorian one, converted automatically. Because the conversion is approximate near month boundaries (for the crescent-sighting reason above), treat the date as a reliable guide while deferring to your local moon-sighting authority for the precise start of Ramadan and the two Eids.
Why the year drifts: a worked example
Because the lunar year is about eleven days shorter than the solar year, an Islamic date arrives roughly eleven days earlier each Gregorian year. If Ramadan begins in early April one year, it will begin in late March the next, mid-March the year after, and so on. Over about thirty-three years it travels all the way around the seasons and back. This is why older Muslims can recall fasting in the depths of winter and, years later, through the long days of summer — the calendar itself moved, not the rules.
Converting between the calendars
Exact conversion is not a simple fixed offset, precisely because month lengths depend on the moon (and, in sighting-based systems, on observation). Tabular methods give a very close approximation by alternating 29- and 30-day months across a fixed 30-year cycle, while observational calendars confirm each month with the crescent. For everyday use the automatic conversion shown on SalatWaqt is more than accurate enough; for the legally significant moments — the start of Ramadan, Eid al-Fitr and Eid al-Adha — communities wait for the official announcement based on their chosen method.
In summary
The Hijri calendar keeps Islamic worship tied to the moon and to the Hijrah. Its gentle drift through the seasons is a feature, not a flaw — it means Ramadan and the pilgrimage rotate through every part of the year over a lifetime.