Ancient Egyptians used a calendar that had 365 days in a year, without exceptions. The year was divided into 12 months of 30 days each, plus 5 extra days (referred to by the ancient Greeks as the epagomenai) after the last month. Because of its great regularity, this calendar was used by ancient Greek and European astronomers until only a few centuries ago.
The names and lengths of the months of the Egyptian calendar are listed in the following table.
Number Name Length 1 Thoth 30 2 Phaophi 30 3 Athyr 30 4 Choiak 30 5 Tybi 30 6 Mecheir 30 7 Phamenoth 30 8 Pharmuthi 30 9 Pachon 30 10 Payni 30 11 Epiphi 30 12 Mesore 30 epagomenai 5
calendar function regards the epagomenai as a 13th month.
The era used for this calendar by the
calendar function is the
Era of Nabonassar, used by Ptolemy, with epoch 26 February -746
C.E. Other eras that have been used elsewhere are the Era of Philippos
(which marks the death of Alexander the Great) starting in year 425 of
Nabonassar, the Era of emperor Hadrian of Rome, starting in year 864 of
Nabonassar, and the Era of emperor Antoninus of Rome, starting in year
885 of Nabonassar.