Twelve Months, a Little Month, and an Era of Martyrs

The Coptic calendar continues the Egyptian civil year the Roman emperor Augustus fixed by decree in 26 BCE: twelve months of thirty days each, three hundred sixty days in all, closed by a small intercalary month of five days, six in a leap year, that the Coptic tradition calls Pi Kogi Enavot, the "little month." The leap rule matches the Julian calendar's exactly, a day added every fourth year with no exception for the century years the Gregorian reform later carved out, so the Coptic year keeps a fixed thirteen day offset from the Gregorian calendar today, an offset that will widen to fourteen days after the Gregorian leap year the Julian reckoning does not skip in 2100. Its era is not counted from Christ's birth but from the accession of the emperor Diocletian in 284 CE, and Coptic tradition calls it the Era of the Martyrs, Anno Martyrum, because Diocletian's reign brought the most severe persecution the Egyptian church endured before Constantine's toleration.

Dating a year from a persecutor's accession, rather than erasing the memory, is a deliberate act of commemoration built into the calendar's arithmetic. The new year, Nayrouz, falls near the eleventh of September, and the small month that precedes it absorbs the calendar's entire correction for the difference between three hundred sixty five days and the true solar year.