Ethiopian calendar is a solar calendar that shares its rules with the Egyptian Coptic calendar, but differs from it in its beginning. Its year consists of 13 months and 365 days for a common/simple year and 366 days for a leap year. It is heavily influenced by Ethiopian Orthodox Church, which follows its own ancient calendar rules and beliefs. Ethiopian calendar is always seven years, seven months, and twenty-eight days behind the Julian calendar.

The Eastern Orthodox Church and Ethiopian Orthodox Church have not accepted the Gregorian calendar and continue to use the Julian calendar with lunar tables for calculating Easter, along with other religious and cultural holidays.

Although the Julian, Gregorian, Coptic, and Ethiopian calendars have the same number of days in a year, the counting rules that determine the number of days in each month and the number of months in a year differ from those of the Ethiopian and Coptic Egyptian calendars.