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Easter Date Calculator

Computes the date of Western (Gregorian) Easter Sunday for any year with the Meeus/Jones/Butcher algorithm and derives Ash Wednesday, Palm Sunday, Good Friday, Ascension Day and Pentecost; also gives Orthodox Easter from the Julian computus converted to the Gregorian calendar.

When to use

You need Easter or the movable feasts tied to it (Lent, Holy Week, Ascension, Pentecost) for a year, including the Orthodox date.

Do not use when: You need fixed-date holidays or non-Christian movable holidays (Passover, Ramadan, Diwali), or dates before 1583 when the Gregorian calendar did not exist.

Formula

Meeus/Jones/Butcher: a = Y mod 19, b = ⌊Y/100⌋, c = Y mod 100, d = ⌊b/4⌋, e = b mod 4, f = ⌊(b+8)/25⌋, g = ⌊(b−f+1)/3⌋, h = (19a+b−d−g+15) mod 30, i = ⌊c/4⌋, k = c mod 4, l = (32+2e+2i−h−k) mod 7, m = ⌊(a+11h+22l)/451⌋; month = ⌊(h+l−7m+114)/31⌋, day = ((h+l−7m+114) mod 31)+1. Orthodox: Meeus Julian algorithm, then Julian date + (⌊Y/100⌋ − ⌊Y/400⌋ − 2) days

Easter is the first Sunday after the ecclesiastical full moon on or after 21 March; the tabular algorithms reproduce the Gregorian and Julian computus exactly for all years. The Julian-to-Gregorian shift is 13 days for 1900–2099.

Inputs

Parameter	Type	Unit	Required	Description
`year`	integer		yes	Gregorian calendar year. Range: ≥ 1583, ≤ 4099

Outputs

Output	Type	Unit	Description
`easter_sunday`	date		Western (Gregorian) Easter.
`ash_wednesday`	date		Easter − 46 days; start of Lent.
`palm_sunday`	date		Easter − 7 days.
`good_friday`	date		Easter − 2 days.
`ascension_day`	date		Easter + 39 days (a Thursday).
`pentecost_sunday`	date		Easter + 49 days.
`orthodox_easter`	date		Eastern Orthodox Easter (Julian computus) expressed as a Gregorian date.
`orthodox_offset_days`	integer	days	Days by which Orthodox Easter follows Western Easter (0 when they coincide).
`golden_number`	integer		Position of the year in the 19-year Metonic cycle: (year mod 19) + 1.

Example

2026: {"year":2026} → {"easter_sunday":"2026-04-05","ash_wednesday":"2026-02-18","palm_sunday":"2026-03-29","good_friday":"2026-04-03","ascension_day":"2026-05-14","pentecost_sunday":"2026-05-24","orthodox_easter":"2026-04-12","orthodox_offset_days":7,"golden_number":13}

2025 (Western and Orthodox Easter coincide): {"year":2025} → {"easter_sunday":"2025-04-20","orthodox_easter":"2025-04-20","orthodox_offset_days":0,"ash_wednesday":"2025-03-05"}

GET https://tttkmbb.com/api/v1/calculate/easter-date?year=2026

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/easter-date (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/easter-date · Markdown: https://tttkmbb.com/time/easter-date.md · JSON definition: https://tttkmbb.com/time/easter-date.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="easter-date"
OpenAPI operationId: calculate_easter_date
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

Date of Easter – Anonymous Gregorian algorithm and Meeus's Julian algorithm (Wikipedia) (reference)
USNO Astronomical Applications – The Date of Easter (government)

FAQ

Why do Western and Orthodox Easter differ?

Orthodox churches keep the Julian calendar and its older lunar tables, so their Easter falls 0, 1, 4 or 5 weeks after the Gregorian date; the two coincide in years such as 2017 and 2025.

What is the possible range of dates?

Western Easter falls between 22 March and 25 April; Orthodox Easter between 4 April and 8 May (Gregorian) during the 20th–21st centuries.

Related calculators

Days Until Calculator — Countdown from today to the Easter date.
Day of the Week Calculator — Weekday and ISO week of any of the feast dates.
Add or Subtract Days Calculator — Shift a feast date by a number of days.