ANA

16.5.57.8: Egyptian Calendar

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

The 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.