A lunar calendar
Each Islamic month begins with the sighting of the new crescent moon, and lasts 29 or 30 days. Twelve lunar months add up to about 354 or 355 days, which is around 11 days shorter than the solar year of 365 days.
That difference is why Ramadan, Eid and Hajj each move about 11 days earlier in the Gregorian calendar every year. Over roughly 33 years, Ramadan passes through every season.
Twelve months
The Quran confirms the number of months:
إِنَّ عِدَّةَ الشُّهُورِ عِندَ اللَّهِ اثْنَا عَشَرَ شَهْرًا فِي كِتَابِ اللَّهِ يَوْمَ خَلَقَ السَّمَاوَاتِ وَالْأَرْضَ مِنْهَا أَرْبَعَةٌ حُرُمٌ“Indeed, the number of months with Allah is twelve months in the register of Allah from the day He created the heavens and the earth; of these, four are sacred.”
- مُحَرَّم Muharram
- صَفَر Safar
- رَبِيع الْأَوَّل Rabi‘ al-Awwal
- رَبِيع الثَّانِي Rabi‘ ath-Thani
- جُمَادَى الْأُولَى Jumada al-Ula
- جُمَادَى الْآخِرَة Jumada al-Akhirah
- رَجَب Rajab
- شَعْبَان Sha‘ban
- رَمَضَان Ramadan
- شَوَّال Shawwal
- ذُو الْقَعْدَة Dhul-Qa‘dah
- ذُو الْحِجَّة Dhul-Hijjah
The four sacred months
The Prophet ﷺ named the four sacred months in his farewell sermon: Dhul-Qa‘dah, Dhul-Hijjah and Muharram, which come one after another, and Rajab (Sahih al-Bukhari 3197).
Why it is called Hijri
The calendar counts years from the Hijrah, the migration of the Prophet ﷺ from Makkah to Madinah in 622 CE. The caliph ‘Umar ibn al-Khattab established this as the starting point. Years are marked AH, from the Latin Anno Hegirae, “in the year of the Hijrah”.
What some month names mean
- Ramadan: from the root ر م ض, linked to intense heat
- Shawwal: linked to lifting or raising
- Muharram: “forbidden” or “sacred”, as one of the sacred months
- Dhul-Hijjah: “the one of the Hajj”, the month of pilgrimage
- Rabi‘: “spring”
The names were given before the calendar became purely lunar, so they no longer match the seasons. Ramadan can fall in winter, and Rabi‘ is not always in spring.
