Easter Date Calculator

How it is calculated

The tool runs the Anonymous Gregorian (Meeus/Jones/Butcher) computus using only whole-number division and remainders. From the year it derives a = year mod 19, the century b and year-in-century c, then a correction h for the moon and l for the weekday, and finally month = (h + l − 7m + 114) div 31 and day = (h + l − 7m + 114) mod 31 + 1. It returns the date as year-month-day plus the month and day numbers. Only years 1583 to 4099 are accepted; outside that range the tool gives no result. The result is the Western (Gregorian) Easter; Orthodox churches that use the Julian calendar often celebrate on a different date.

Common mistakes

• Expecting a date for years before 1583; the Gregorian calendar did not exist then, and the tool returns nothing for them.
• Comparing the result with the Orthodox Easter date, which is calculated on the Julian calendar and is frequently a different Sunday.
• Entering a two-digit year such as 25 instead of 2025.
• Treating the astronomical full moon as the basis; the method uses the church's tabulated moon, so it can differ from the real sky.