The Ethiopian calendar (Amharic: ዐውደ ወር; Ge'ez: ዐውደ ወርኅ; Tigrinya: ዓዉደ ኣዋርሕ), or Geʽez calendar (Geʽez: ዐውደ ወርኅ; Tigrinya: ዓዉደ ኣዋርሕ, Amharic: የኢትዮጲያ ዘመን አቆጣጠር) is the official state civil calendar of Ethiopia and serves as an unofficial customary cultural calendar in Eritrea, and among Ethiopians and Eritreans in the diaspora. It is also an ecclesiastical calendar for Ethiopian Christians and Eritrean Christians belonging to the Orthodox Tewahedo Churches (Ethiopian Orthodox Tewahedo Church and Eritrean Orthodox Tewahedo Church), Eastern Catholic Churches (Eritrean Catholic Church and Ethiopian Catholic Church), and Protestant Christian P'ent'ay (Ethiopian-Eritrean Evangelical) Churches. The Ethiopian calendar is a solar calendar that has much in common with the Coptic calendar of the Coptic Orthodox Church of Alexandria and Coptic Catholic Church, but like the Julian calendar, it adds a leap day every four years without exception, and begins the year on 11 or 12th of September in the Gregorian calendar (from 1900 to 2099). Its epoch (first day of first year) equates to 29 August 8 AD. The neighbouring Coptic calendar is very similar to the Ethiopian calendar, except that it has a different epoch (29 August, 284 AD) and different names for the days of the week and months of the year.
The Ethiopian calendar has twelve months, all thirty days long, and five or six epagomenal days, which form a thirteenth month. The Ethiopian months begin on the same days as those of the Coptic calendar, but their names are in Geʽez. A sixth epagomenal day is added every four years, without exception, on 29 August of the Julian calendar, six months before the corresponding Julian leap day. Thus, the first day of the Ethiopian calendar year, 1 Mäskäräm, for years between 1900 and 2099 (inclusive), is usually 11 September (Gregorian). It falls on 12 September in years before the Gregorian leap year, however.
