How do they figure the date for Easter?

The date for Easter was set to trap the full moon, but the plan was not entirely successful. The key date from which Easter is reckoned is taken from an ancient lunar calendar. However, this old calendar was not based accurately on the phases of the moon. The key date was the Pascal Full Moon occurring in March and Easter was set for the full moon following this date.

The plan was made at the Council of Nicea in 325 A.D. It was meant to help the pilgrims who needed to travel by moonlight during the great festival. Easter can fall between March 21 and April 25, but the date does not guarantee a full moon. This year, Easter Day is April 22, and the moon will not be full.