Easter is one of the Christian religious holidays without a fixed calendar date. It is celebrated on the first Sunday after the first ecclesiastical full moon following the spring equinox in the Northern Hemisphere. The Catholic Church uses March 21 to mark the spring equinox in order to calculate this date, even though the equinox can technically fall between March 19-21.
U.S. Census Bureau data shows that in the 500 years from 1600 to 2099 AD, Easter is most frequently celebrated on March 31 or April 16 (22 times each) and least frequently celebrated on March 24 (twice) and March 22 (three times). The earliest possible date it can fall on is March 22 and the latest is April 25. This year, the date lands on April 20, while next year it will be April 5.