The Coptic and Ethiopian Calendars

The Julian year was introduced in Egypt by inserting a sixth additional day every four years, leaving the lengths of the other months unchanged (see Egyptian calendar). This calendar, called Alexandrinian calendar remained in use for several centuries. Merchants from the Byzantine Empire and other Christian countries brought this calendar to Aksum, an empire located in the northern part of what is now Ethiopia. King Ezana of Aksum eventually took the Christian belief in the fourth century introducing also the Alexandrinian calendar. In northern Africa the Alexandrinian calendar was succeeded by the Islamic calendar in the 7th century and remained in use by a small Christian (Coptic) minority only.

In a dispute with the Roman Church the Alexandrian Church maintained monophysitism, stating that the human and divine constitute only one nature in the person of Jesus Christ. On the council of Chalcedon (today Kadiköy) the existence of two natures in Christ became the official doctrine in 451. After that, the Alexandrinian Church separated from the Roman Church. However, a Roman patriarchate existed in Alexandria until the Islamic conquest. Its influence was limited to the local Greek population, the Egyptians following the new Coptic church created by the separation. Also the Ethiopic Church did not follow the Chalcedonian doctrine. Both the Coptic and the Ethiopic churches continued to use the Alexandrinian calendar.

Months and Leap Year Pattern

The number and lengths of months in the Coptic and Ethiopian calendars are the same as those of the Alexandrinian calendar. A year consists of twelve months with 30 days each followed by five or, in leap years, six additional days, every fourth year being a leap year. The table below shows lengths and names of the months in both calendars.

No.	Coptic	Ethiopic	Common Year	Leap Year
No.	Coptic	Ethiopic	Length
1	Thoout	Maskarram	30	30
2	Paape	Tekemr	30	30
3	Hator	Hadar	30	30
4	Kiahk	Tahsas	30	30
5	Tobe	Tarr	30	30
6	Mshir	Yekatit	30	30
7	Paremhat	Makawit	30	30
8	Parmoute	Miaziah	30	30
9	Pashons	Genbot	30	30
10	Paone	Sanni	30	30
11	Epep	Hamle	30	30
12	Mesore	Nashi	30	30
13	Paguemen	Quaggimi	5	6

Since the leap year pattern is the same as in the Julian calendar a certain date in the Coptic/Ethiopic calendar corresponds to a certain date in the Julian calendar with the exception of the period from 29 August to 29 February in a Julian calendar common year that is followed by a Julian calendar leap year. Within this period, Julian 29 August is the sixth additional day of the Coptic/Ethiopian calendar instead of Coptic/Ethiopian New Year, thus shifting the dates by one day.

Epochs

The Coptic calendar counts the years according to the "Era of Martyrs", i. e. the Era of Diocletian, that starts on 29 August 284 (Julian). The Ethiopic calendar's epoch is 29 August 7 CE (Julian).

Feast Days

Easter always falls on the same day as in the Julian calendar. Thus, the date of Easter can be determined using the Julian rules and then transformed into the corresponding Coptic or Ethiopian date. Easter can fall on any date from 26 Paremhat through 30 Parmoute, inclusive. Some fixed holidays are Epiphany (11 Tobe), Mary's Announcement (29 Paremhat), and Christmas (29 Kiahk).