How is the date of Easter calculated?

Unlike Christmas, which is fixed on 25 December, Easter Sunday moves every

year. It can fall anywhere between 22 March and 25 April. The rule is simpler

than it looks.

The rule

Easter Sunday is the first Sunday after the first full moon that falls on or

after the spring equinox, which is fixed at 21 March for this purpose.

Because both the full moon and the day of the week move, the date of Easter

changes from year to year.

The calculation is called the **computus**. The Gregorian version, used by

most Christian churches today, is an algorithm that works out the date

directly from the year number. It was introduced with the Gregorian calendar

in 1582 and corrects for the small difference between the lunar year and the

solar year.

Several other holidays are fixed relative to Easter:

This is why Ash Wednesday and Carnival always follow the same cycle, and why

the whole Easter season moves together each year.

Use the Easter date calculator to see the upcoming dates, or

browse the full Easter cycle with links to every related

holiday in every country.