Islam
The Islamic Calendar: Lunar Calculation and Important Dates
· 8 min read
The Islamic calendar is a time measurement system based on moon phases. Learn how it is calculated, its months, and the most important dates of the year.
The Islamic Calendar
History
The Islamic calendar was established during Umar ibn al-Khattab's caliphate in 638 CE (17 AH). The Hijrah (migration to Medina, 622 CE) was chosen as the starting point because it marked the Muslim community's attainment of religious and political freedom.
Lunar Calculation
Each month begins with the new moon (hilal). The month lasts 29 or 30 days. The year has 354 or 355 days. To keep the calendar synchronized with the moon, 11 days are intercalated every 30 years.
Determination Methods
Two methods exist:
- Visual sighting: traditional, requires seeing the new moon with the naked eye
- Astronomical calculation: modern, uses astronomical predictions
Important Dates
- 1 Muharram: New Year
- 10 Muharram: Ashura
- 12 Rabi' al-Awwal: Mawlid al-Nabi
- 27 Rajab: Isra wal-Mi'raj
- 15 Sha'ban: Nisf Sha'ban
- 1-29/30 Ramadan: fasting month
- 1-3 Shawwal: Eid al-Fitr
- 9 Dhul-Hijjah: Day of Arafah
- 10-13 Dhul-Hijjah: Eid al-Adha
The Complete Cycle
Every 33 years, Islamic dates complete a cycle through all seasons. Ramadan can fall in winter (short fast) or summer (long fast), alternating throughout a person's lifetime.
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