Easter Date Calculator (Western & Orthodox Easter for any year)

Understanding the Easter date calculator — concept and principle

This calculator finds the date of Western and Orthodox Easter Sunday for any year from 1583 to 4099, along with Ash Wednesday, Good Friday, Ascension Day and Pentecost. Use it to plan holidays, school terms, church events or travel years ahead.

Finding Easter 2027: with the default inputs the result is Sun, Mar 28, 2027 (Orthodox: May 2, 2027).

How it is calculated

Western Easter uses the Gregorian computus published by Jean Meeus (after Butcher, 1876): a series of integer divisions of the year gives the golden number (year mod 19), century corrections for the leap-year rule and the Moon, the epact, and finally the month and day.
Orthodox Easter uses Meeus's Julian algorithm with the older 19-year lunar cycle; the Julian date is converted to the Gregorian calendar by adding the calendar difference, 13 days from 1900 to 2099.
Ash Wednesday = Easter − 46 days; Good Friday = Easter − 2; Ascension = Easter + 39; Pentecost = Easter + 49.

The principle

Easter is the first Sunday after the ecclesiastical full moon that falls on or after 21 March. The "ecclesiastical" moon is a table-based approximation, not the real astronomical moon, so the dates can be computed exactly with arithmetic. Every 19 years the Moon's phases fall on almost the same calendar dates (the Metonic cycle), which is why year mod 19 appears. Western churches use the Gregorian calendar and lunar tables, so Western Easter falls from 22 March to 25 April. Orthodox churches keep the Julian calendar and the older tables, so their Easter is often later.

Worked example

Default input: year 2027.

The Gregorian algorithm gives Sun, Mar 28, 2027 for Western Easter.
Ash Wednesday = Mar 28 − 46 days = Wed, Feb 10, 2027; Good Friday = Fri, Mar 26, 2027.
Ascension = Mar 28 + 39 days = Thu, May 6, 2027; Pentecost = + 49 days = Sun, May 16, 2027.
The Julian algorithm, plus 13 days, gives Orthodox Easter Sun, May 2, 2027.
Gap = 35 days = 5 weeks.

How to read the result

In some years the two Easters fall on the same Sunday; in others they are one, four or five weeks apart. The movable feasts shown are those of the Western calendar; Orthodox churches count their own feasts from Orthodox Easter. Public holidays tied to Easter, such as Good Friday or Easter Monday, depend on each country's law.

Common mistakes

Assuming Easter follows the astronomical full moon; it uses church tables.
Using Western Easter for Orthodox events.
Counting Ash Wednesday as 40 days before Easter; Sundays are not counted in Lent, so it is 46 days.
Entering a year before 1583, before the Gregorian calendar was in general use.

Keep in mind: Some churches and countries follow local rules or revised calendars. Check with your church or official holiday list for local observances.

Frequently asked questions

When is Easter in 2027?

Western Easter is Sunday 28 March 2027 and Orthodox Easter is Sunday 2 May 2027.

What is the earliest and latest possible Easter date?

For Western Easter, 22 March and 25 April.

Why do Western and Orthodox Easter differ?

The Orthodox churches use the Julian calendar and older lunar tables, which usually put Easter later.

Sources: J. Meeus, Astronomical Algorithms, 2nd ed. (Willmann-Bell, 1998), ch. 7–8

Checked 9 Nov 2026. J. Meeus, Astronomical Algorithms, 2nd ed. (Willmann-Bell, 1998), ch. 8 “Date of Easter” — Gregorian algorithm (after S. Butcher, Ecclesiastical Calendar, 1876) and Julian algorithm; Julian-to-Gregorian difference from the same book, ch. 7.

Your numbers