HMEPA : Hellenic Month Established Per Athens

Visit the calendar.

This calendar is the Athenian calendar, updated to be a calendar for the modern world. It follows the spirit of the ideal calendar, being lunisolar and based on the visibility of the crescent. But it compromises by using a calculation and by basing it on visibility not at Athens itself, but with adjustment so that the visibility somewhere in the populated world is the criterion.

In Athens they weren’t very concerned with calendar accuracy, and setting the calendar was a political act. So it is unlikely that any date in this calendar corresponds to a historical date in Athens.

Basic principles of the calculation

  • The day for any location begins/ends at sunset at that location.
  • The year begins with Hekatombaion, the first month which begins after the summer solstice, in Athens.
  • The first olympiad was in the summer (beginning of attic year) of the year 776 BC; that is, the year beginning in the summer of 776BC was the first year of the first olympiad.
  • The calendar is international, but based on the city of Athens.

Any international calendar faces the problem of the date line. We use an international date line which corresponds to the current international Gregorian date line, in the Pacific Ocean, since this offers a geographically convenient dividing line.

The day and month begins based on local sunset on the same international day as it begins in Athens. Thus the day can always be said to begin at sunset on a given Gregorian date. For example, Hekatombaion of the 4th year of the 694th olympiad begins at sunset on July 2, 2000.