Tabular Islamic calendar

The Tabular Islamic calendar is a rule-based variation of the <a href="/facts/Islamic_calendar/7n4UBAYy">lunar Hijri cakendar</a>. It has the same numbering of years and months, but the months are determined by arithmetical rules rather than by observation or astronomical calculations. It was developed by early Muslim astronomers of the second hijra century (the 8th century of the <a href="/facts/Common_Era/e5DpqUoe">Common Era</a>) to provide a predictable time base for calculating the positions of the Moon, Sun, and planets. It is now used by historians to convert an Islamic date into a Western calendar when no other information (like the day of the week) is available. Its <a href="/facts/Calendar_era/3Qjnadec">calendar era</a> is the <a href="/facts/Hijri_year/YLhMRWU1">Hijri year</a>. An example is the <a href="/facts/Fatimid_Caliphate/jgmF2I5C">Fatimid</a> or Misri calendar.
Each year has 12 months and 354 or 355 days. The odd numbered months have 30 days and the even numbered months have 29 days, except in a <a href="/facts/Leap_year/7Vfs3cTg">leap year</a> when the 12th and final month Dhu al-Hijjah has 30 days.
Virtually all Muslims use an observation-based calendar for religious purposes such as the <a href="/facts/Islamic_calendar/7n4UBAYy">Umm al-Qura calendar</a>, accounting for the non-uniform motions of the Sun and the Moon and other factors, and use the tabular calendar only for approximation (because dates predicted by the tabular Islamic calendar can occur one or two days too early or too late).

Tabular Islamic calendar open-in-new

Tabular Islamic calendar