When is Easter? Any year, Western and Orthodox.

How to read the result

Easter is the first Sunday after the Paschal full moon, the first full moon on or after March 21 (Wikipedia, “Date of Easter”). That moon is a reckoned one, kept in the churches’ tables. It is not the moon in the sky: the official full moon can differ from the real one by a day or two (The Calendar FAQ).

Two reckonings are in use, which is why the calculator gives two dates. Western churches count in the Gregorian calendar. Orthodox churches count in the older Julian calendar, even where they otherwise keep the Gregorian one (The Calendar FAQ), so their Easter, Pascha, usually comes later. The Orthodox date is shown here in the Gregorian calendar, the one on the wall.

Western Easter always falls from March 22 to April 25: 35 possible dates, the upper band on the strip. In the 201 years from 1900 to 2100 the two Easters fall on the same day in 57 years; in the rest the Orthodox date is one week later in 91 years, four weeks later in 9 years, five weeks later in 44 years. The years both Easters coincide are listed on their own page, and the earliest and latest Easters on another.

Which years it covers

The calculator takes any year from 1583 to 9999. The Gregorian calendar went into effect in October 1582 (Wikipedia, “Gregorian calendar”), so 1583 is the first Easter reckoned in it. For the Orthodox date the distance between the two calendars is worked out for each year, never typed in: it is 13 days from 1900 to 2099 and 14 days from 2100. Far-future dates are arithmetic, not prediction. The rules are conventions, and the churches could change them (Wikipedia, “Date of Easter”).

The feasts, and who keeps them

Once Easter is known the rest follow by counting. Ash Wednesday is 46 days before Easter (Wikipedia, “Ash Wednesday”) and Shrove Tuesday is the day before it (Wikipedia, “Shrove Tuesday”). Palm Sunday is the Sunday before Easter (Wikipedia, “Palm Sunday”). Ascension is the fortieth day of Easter, counting Easter Sunday itself, which makes it a Thursday (Wikipedia, “Feast of the Ascension”). Pentecost is the 49th day after Easter (Wikipedia, “Pentecost”). In the Orthodox calendar Clean Monday, the first day of Great Lent, is 48 days before Pascha (Wikipedia, “Clean Monday”).

Observance varies by church and by country. Some churches keep Ascension on the following Sunday (Wikipedia, “Feast of the Ascension”). Whether a feast is a day off work is a matter of each country’s law: Holidays lists each country’s public holidays, off the open Nager.Date database.

How the dates are checked

Nothing on these pages is looked up. Each date is computed in your browser by the Anonymous Gregorian algorithm and by Meeus’s Julian algorithm; how Easter is calculated walks through both. The same arithmetic is written a second time in the program that prints these pages, and the two are compared year by year and then against published tables. For the printed years the US Census Bureau table agrees in 200 of 200 years it covers and the 5ko.free.fr tables in 201 of 201. The full list of checks is on the about page.