Understanding the Hijri calendar and its twelve sacred months
Introduction
The Islamic Calendar, known in Arabic as the Hijri calendar (AH, Anno Hegirae), is the official calendar of Islam and the basis for determining religious obligations, festivals, and the timing of the Hajj pilgrimage. It is a purely Lunar Calendar system of twelve months, each lasting 29 or 30 days, for a total of 354 or 355 days per year.
The Twelve Months
The Islamic year consists of the following months in order: Muharram, Safar, Rabi al-Awwal, Rabi al-Thani, Jumada al-Awwal, Jumada al-Thani, Rajab, Sha'ban, Ramadan, Shawwal, Dhu al-Qi'dah, and Dhu al-Hijjah. Four of these — Muharram, Rajab, Dhu al-Qi'dah, and Dhu al-Hijjah — are considered sacred months during which warfare was traditionally forbidden.
The Epoch: The Hijra
Year 1 AH corresponds to 622 CE on the Gregorian Calendar, the year the Prophet Muhammad emigrated from Mecca to Medina — an event known as the Hijra. The calendar was formalized during the reign of the Caliph Umar ibn al-Khattab around 638 CE. The year 2026 CE corresponds approximately to the years 1447-1448 AH.
Key Holidays and Their Lunar Basis
Ramadan, the ninth month, is the month of fasting observed by Muslims worldwide. It begins with the sighting of the crescent moon and ends with the celebration of Eid al-Fitr on the first day of Shawwal. Because the Islamic year is eleven days shorter than the solar year, Ramadan advances about eleven days earlier in the Gregorian Calendar each year, rotating through all seasons over a 33-year cycle.
Eid al-Adha, the Festival of Sacrifice, falls on the tenth day of Dhu al-Hijjah and coincides with the culmination of the annual Hajj pilgrimage to Mecca. It is the more solemn of the two Eids and is observed as a public holiday in many Muslim-majority countries for three to four days.
Islamic New Year
Muharram 1 marks the Islamic New Year, though the occasion is observed quietly rather than with large festivities. The tenth day of Muharram, Ashura, holds particular importance — for Sunni Muslims it is a day of voluntary fasting; for Shia Muslims it is a day of mourning commemorating the martyrdom of Imam Husayn at Karbala.
Moon Sighting Controversy
The question of whether month-start depends on local crescent sighting or global calculation remains a point of scholarly debate. Saudi Arabia, Pakistan, and many South Asian communities rely on physical sighting, while some communities in North America and parts of Europe follow astronomical pre-calculation. This can result in Eid being celebrated on different days in different countries — or even within the same country.
Using the Islamic Calendar
For planning purposes, published Hijri-Gregorian conversion tables provide approximate dates for Islamic holidays years in advance. These are accurate within a day or two, subject to actual moon sighting. Business travelers to Muslim-majority countries should confirm local public holiday schedules directly, as office closures during Eid can extend from one to six days depending on the country.
Conclusion
The Islamic calendar is a precisely designed lunar system rooted in both astronomical observation and religious law. Its annual drift through the Gregorian year is not an inconvenience but a theological feature, ensuring that no season has a permanent claim on Islam's sacred months.