How are Easter dates determined for future years?

The observation of Easter occurs on the Sunday following the first full moon on or after the spring equinox. It does not fall on a fixed date. This dating method was set by the Council of Nicaea in 325 A.D.

There have been several reform efforts to solidify the date of Easter in order to make it more predictable. Annual fluctuations in the date lead to difficulties in academic calendars and civic planning. In addition, Christian churches in the East and West use different calendars. As a consequence, Easter celebrations occur on two different dates, depending on the church's geographical location. Reform efforts seek to come up with a unified date for the holiday for all churches worldwide.