Coptic (Anno Martyrum) calendar converter

The Era of the Martyrs

The Coptic calendar counts its years from 284 CE, the accession of the Roman emperor Diocletian. His reign brought the most violent persecution Egypt's Christians had faced, and the Coptic church chose to date its years from that suffering rather than erase it: Anno Martyrum, the Year of the Martyrs. The structure of the calendar is far older. It descends directly from the ancient Egyptian civil calendar, the same twelve months of thirty days plus a short final stretch that Egypt had kept for millennia.

Thirteen months and the little month

Twelve months of exactly thirty days run from Thout through Mesori, then a thirteenth month called Nasie (from the Greek epagomenai, "days added on") carries five days, or six in a leap year. The Coptic leap rule is the simple Julian one: every fourth year. This is the same frame the Ethiopian calendar inherited, which is why the two run in lockstep, separated only by their different starting epochs.

Nayrouz, the Cross, and the Coptic liturgical year

The year opens with Nayrouz on 1 Thout, falling on 11 September (or 12 in the year before a Gregorian leap year). Sixteen days later comes the Feast of the Cross. Coptic Christmas, the Nativity, is kept on 29 Koiak, which lands on 7 January Gregorian, and Theophany follows on 11 Tobi (19 January). Coptic Easter (Pascha) uses the Julian-rule paschal computation, so it usually falls a week or more after western Easter, in step with the Eastern Orthodox and Ethiopian churches.