How the Islamic calendar works

The Hijri calendar is lunar: each month begins with the sighting of a new crescent, and a year is roughly eleven days shorter than the Gregorian year. Because sighting depends on location and atmosphere, the first day of a Hijri month can vary between communities. The calendar on this page uses a tabular arithmetic conversion, which gives a consistent calculated date rather than a locally confirmed sighting. Every date frame on the page labels that distinction.

The monthly grid shows Gregorian days alongside their calculated Hijri equivalents, and the current date panel can be inspected without changing today’s real date. The converter works in both directions: enter a Gregorian date to see the Hijri result, or a Hijri day, month, and year to see the corresponding Gregorian date. Invalid dates, such as a day beyond the length of a Hijri month, are rejected with an explanation.

Key Observances lists the calculated dates for the current Hijri year, including Ramadan, Eid al-Fitr, Eid al-Adha, and the first ten days of Dhul-Hijjah. These are planning aids: local mosques and authorities may announce a different day. For the daily prayer schedule that accompanies the calendar, use prayer times.