As a moveable feast, the date of Easter is determined in each year through a calculation known as computus (Latin for computation). Easter is celebrated on the first Sunday after the Paschal full moon, which is the first full moon on or after 21 March (a fixed approximation of the March equinox).

What fixes the date of Easter?

The ecclesiastical rules are: Easter falls on the first Sunday following the first ecclesiastical full moon that occurs on or after the day of the vernal equinox; this particular ecclesiastical full moon is the 14th day of a tabular lunation (new moon); and the vernal equinox is fixed as March 21.

Why Easter has no fixed date?

Easters exact date varies so much because it actually depends on the moon. The holiday is set to coincide with the first Sunday after the Paschal Full Moon, the first full moon after the vernal equinox. Because the Jewish calendar is tied to solar and lunar cycles, the dates of Passover and Easter fluctuate each year.

Will Easter be fixed?

Easter is a “movable feast” and does not have a fixed date. However, it is always held on a Sunday between March 22 and April 25. Over a 500-year period (from 1600 to 2099 AD), it just so happens that Easter will have most often been celebrated on either March 31 or April 16.

How late can Easter be in the year?

The earliest possible date for Easter is March 22 and the latest possible date is April 25. Easter can never come as early as March 21, however. Thats because, by ecclesiastical rules, the vernal equinox is fixed on March 21.