hijriah

Hijriah, or the Hijri calendar, is an Islamic lunar calendar used to date events and religious observances within the Muslim world. It traces its origin to the Hijra, Prophet Muhammad’s migration from Mecca to Medina in 622 CE. The calendar is counted in years of the Islamic era (AH, Anno Hegirae) and begins with 1 Muharram AH 1, the year traditionally associated with the Hijra.

The calendar consists of 12 lunar months: Muharram, Safar, Rabiʿ al-awwal, Rabiʿ al-thani, Jumada al-ula, Jumada al-akhira, Rajab, Shaʿaban, Ramadan, Shawwal, Dhu al-Qiʿdah, and Dhu al-Hijjah. Each month begins with the sighting of the new crescent moon or other criteria used by different authorities. A common year has 354 days and a leap year has 355 days, with leap years occurring in a 30-year cycle. Because it is based on the lunar cycle, the Hijri year is about 11 days shorter than the solar year, causing the months to drift through the seasons over time.

Hijriah is primarily used to determine the dates of religious events, including Ramadan, the Hajj and Eid al-Fitr and Eid al-Adha. In many countries, the Gregorian calendar is used for civil purposes, while the Hijri calendar remains central to religious life and cultural identity. Some communities rely on moon sighting to determine month starts, whereas others use astronomical calculations or tabular calendars to estimate dates. Converting between Hijri and Gregorian dates is possible with algorithms and reference tables, but exact dating can vary by local practice.