Calculating the date for Easter (Latin computes) is the way that you determine the dates for Easter according to the church calendar. Easter is the oldest and most important event for Christians. That is the date when Jesus Christ arose from the dead. The celebration of Easter started in the second or beginning of the third century AD by the Jewish lunar calendar and it coincides with Jewish Passover, which happens on the 14th day of the month of Nissan – the month that the Jews came out from under Egyptian slavery.

After the first church council which took place in Nicaea, Turkey in the year 325 AD and until 1582, Easter was calculated according to the Julian calendar. The Gregorian calendar, named after Pope Gregory XIII was an adaptation of the Julian calendar and today remains valid for the entire Christian world. All the events that took place before 15th October, 1582 AD if not described differently, are calculated according to the Julian calendar.

According to the gospels, Jesus Christ died the night before Passover which is on the 14th of Nissan (on that day there is a full moon) and His resurrection took place on the Sunday following that date. Churches in the Middle East always celebrate Easter on the 14th of Nissan, regardless of which day of the week it falls on. The other churches celebrate Easter on the Sunday following 14th of Nissan and for this reason the actual date of Easter is not fixed.

In the Catholic Church, the date of Easter is always after the 14th Nissan and occurs after the 21st of March. It is for this reason that the date of Easter varies and falls between the 22nd of March and the 25th of April.

In brief, Easter is always on the first Sunday following the Equinox when there is a full moon!

Example

In 2011, the 21st March was Spring Equinox and on the 18th of April there is a full moon and the first Sunday after that is the 24th of April - Easter Sunday!

Note

In churches using the Julian calendar, there is an additional rule. Easter has to be after Passover and therefore does not coincide with Jewish Passover. However, in churches following the Gregorian calendar, Easter falls according to a different calculation and therefore often does not fall on the same dates as the Julian calendar. See attached table.