Easter Date Calculator

How Easter's date is actually defined

Western (Gregorian) Easter is defined as the first Sunday after the first full moon on or after the spring equinox — but for calendar purposes, churches don't use the real astronomical moon. They use a set of fixed ecclesiastical rules (a system called the Computus) that approximate it, standardized so every diocese lands on the same date without needing an astronomer. This tool implements that standard rule set directly — the same "Anonymous Gregorian algorithm" used in most software and reference almanacs — so every date is calculated, not looked up.

Why it moves by more than a few days some years

Because Easter tracks a lunar cycle superimposed on the solar calendar, its earliest possible date is March 22 and its latest is April 25 — a five-week range, far wider than most "movable" holidays. Eastern Orthodox Easter, which follows the Julian calendar's equinox and lunar tables instead, often falls on a different date entirely, sometimes weeks apart from the Western date.