Welcome to our Easter calculator. In the Western (most Protestant denominations and Roman Catholic) Church, Easter falls on the first Sunday following the first full moon following the Vernal (Spring) Equinox in the northern hemisphere. Because of its dependence on the phase of the moon, Easter is referred to as a "moveable feast". Certain other Holy Days vary with the date of Easter - Shrove Tuesday (Mardi Gras), Ash Wednesday, Palm/Passion Sunday, Holy (Maundy) Thursday, Good Friday and Pentecost (Whitsun) are all dependent on the date of Easter. For a description of these terms, we have both a Liturgical Calendar and a Glossary of Lenten and Easter terms.

This calculator will accurately return the date of Easter in the Western Church for all years using the Gregorian Calendar. The Gregorian Calendar was introduced in 1582 by Pope Gregory XIII, and was in use in most Catholic countries by they following year. Acceptance of the Gregorian Calendar in Protestant countries and the rest of the world was gradual, with the United Kingdom and its colonies (including the American Colonies) adopting it in 1752, while it was not accepted in Russia until 1918.

Easter in the Orthodox Church is calculated using a different algorithm, which can coincide with Easter in the Western Church, or may be between one to five weeks later.