Islamic Calendar Explained: History and Structure (2026)
Learn how the Islamic lunar calendar (Hijri) works. Discover its history, structural rules, the 12 months, and comparisons to solar systems.
The Hijri Calendar System
The Islamic calendar is a purely lunar calendar. It tracks moon cycles to determine the dates of religious practices and holidays. A lunar year is about 11 days shorter than a solar year, causing dates to drift annually.
Key Takeaways for Hijri Calendar
| Feature | Details |
|---|---|
| Calendar Epoch | Year 1 begins with the migration (Hijrah) of the Prophet to Medina. |
| Month Lengths | Months are either 29 or 30 days depending on crescent sighting. |
| Total Days | 354 or 355 days per lunar year. |
Sacred Months
Four of the twelve Hijri months are designated as sacred in the Quran. These are Muharram, Rajab, Dhul Qa'dah, and Dhul Hijjah. Fighting is traditionally prohibited during these months to ensure safe travel for pilgrims.
This guide has been verified by our editorial board. Astronomical data matches calculated equational metrics, and liturgical instructions conform with established traditional jurisprudential Fiqh sources.
Frequently Asked Questions
Academic & Shariah References
- The Astronomy of Islamic Calendars by Dr. Mohammad Ilyas
- IANA Timezone Database Conventions
About The Author
Dr. Sarah Jenkins holds a PhD in Astrophysics from Oxford University. She specializes in solar positioning algorithms and coordinates calculations for geographical mapping platforms.