Why Easter changes every year

Easter is on a different day each year because it is tied to the Moon and the spring equinox, not to a fixed calendar date. The usual rule is: Easter falls on the first Sunday after the first full moon on or after March 21.

The short version

That means Easter can land anywhere from March 22 to April 25. Because the full moon and Sunday shift from year to year, the holiday moves too.

Why that rule exists

The date was set this way in early Christian tradition, so Easter would be linked to spring and would not be the same day as Passover. The Church also uses an ecclesiastical March 21 as the fixed spring equinox for the calculation.

Quick example

If the first full moon after March 21 happens on a Friday, Easter is the very next Sunday. If it happens on a Sunday, Easter is still the following Sunday.

One more wrinkle

Eastern Orthodox and Western churches do not always celebrate Easter on the same date because they use different calendar systems for the calculation. That is why Easter can also differ by several weeks depending on the tradition.

Easter “moves” because it follows a lunar-plus-solar rule instead of a fixed date.

Meta description: Easter changes every year because it is calculated as the first Sunday after the first full moon on or after March 21.

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TL;DR: Easter is a movable feast, so its date changes each year based on the Moon and the spring equinox.

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