Easter Date Calculator
Compute Western and Eastern Orthodox Easter for any year.
Overview
The Easter Date Calculator computes the date of Easter Sunday for any year between 1583 and 9999, for both the Western (Gregorian) and Eastern Orthodox (Julian-based) churches. Enter a year and you get two dates — one used by Roman Catholic and Protestant churches, the other by Greek, Russian, Serbian, and other Orthodox traditions — along with the gap between them.
Useful for clergy planning Holy Week services, school administrators scheduling around the Easter break, retail planners stocking seasonal merchandise, and developers building calendar apps that need to display Christian holidays alongside secular ones.
How it works
Western Easter is determined by the Gauss-Butcher anonymous algorithm, the standard computus that has been refined since the Council of Nicaea (325 AD) and last adjusted in the Gregorian reform of 1582. It locks Easter to the first Sunday after the first ecclesiastical full moon on or after March 21. The result lands between March 22 and April 25 inclusive.
Eastern Orthodox Easter follows the older Julian-calendar version of the same rule. Because the Julian calendar drifts about three days per four centuries against the Gregorian, Orthodox Easter currently runs zero to five weeks later than Western Easter, with the two dates coinciding roughly one year in four.
Examples
2026 → Western: Apr 5 Orthodox: Apr 12 (1 week apart)
2024 → Western: Mar 31 Orthodox: May 5 (5 weeks apart)
2025 → Western: Apr 20 Orthodox: Apr 20 (same date)
2027 → Western: Mar 28 Orthodox: May 2
FAQ
Why does Easter move every year?
Easter follows a lunar-solar rule — the first Sunday after the first full moon on or after the spring equinox — rather than a fixed date. The full-moon component shifts the date across a 35-day window.
What is the earliest and latest possible Easter?
Western Easter ranges from March 22 to April 25. Orthodox Easter ranges from April 4 to May 8 in Gregorian dates.
Why are the Western and Orthodox dates often different?
Both churches use the same computus rule but apply it on different calendars — Gregorian for the West, Julian for the East — and the Julian calendar lags the Gregorian by 13 days in the modern era.
When do they coincide?
About once every three to four years on average. Notable shared years include 2014, 2017, and 2025.
Does the algorithm work before 1583?
Western dates are computed from 1583 onward (the year after the Gregorian reform). For earlier years, Easter was calculated on the Julian calendar by definition.