Easter is decided by a simple rule: it falls on the first Sunday after the first full moon on or after March 21. That is why the date changes every year, usually landing anywhere from March 22 to April 25.

Quick Scoop

  • The spring equinox is fixed at March 21 for the calculation.
  • The next qualifying full moon is called the Paschal Full Moon.
  • Easter is then celebrated on the following Sunday.

Why it moves

The date is not based on one exact astronomy observation each year; churches use calendar rules and tables that approximate the moon cycle.

That system was settled long ago, especially through the Council of Nicaea in AD 325 , which aimed to make Easter’s timing consistent across Christian communities.

In one line

If you want the shortest version: find the first full moon after March 21, then go to the next Sunday.