What this calculator does
Find out when Easter Sunday falls in any year, and the dates of the days around it. Easter is not tied to one date like Christmas. It moves between late March and late April, and sometimes into May for Orthodox churches. That can make it hard to plan school breaks, trips or family get-togethers far ahead.
Enter a year and pick a tradition. The calculator gives the date of Easter Sunday and a few related days, such as Good Friday and Pentecost. It also lists Easter for the next ten years. The steps show the counting method churches have used for centuries. You can follow it with pencil and paper.
Where it's used
Why this math matters outside the classroom:
- School calendars. District planners place spring break around Easter, which falls on April 16 in 2028 and April 1 in 2029.
- Travel planning. Families booking a spring trip see that Good Friday is March 26 in 2027 but April 14 in 2028.
- Church scheduling. Parish offices count 46 days back from Easter, March 28, 2027, to set Ash Wednesday on February 10.
- Classroom remainders. Students find 2027 mod 19 = 13 by dividing 2027 by 19 and keeping the remainder of 13.
- Shared holidays. Mixed families note that Western and Orthodox Easter both fall on April 16 in 2028 and plan one celebration.
How to use it
- Type the year you want, from 1583 to 4099. It starts at 2027.
- Pick Western for the date most Catholic and Protestant churches use, or Orthodox for the Eastern Orthodox date.
- Read Easter Sunday at the top, then the related days below it.
- Open the table to see the next ten years, both traditions side by side. Open the steps to see how the date is worked out.
What the inputs mean
- Year
- The Western method starts in 1583, the first full year of the Gregorian calendar (the calendar most of the world uses today). The calculator stops at 4099, since calendar rules that far ahead may well change. Both traditions use the same range here.
- Tradition
- Western churches use the Gregorian calendar to set Easter. Most Orthodox churches still set it with the older Julian calendar. The calculator then moves that date onto today's calendar, so both answers are dates you can put in a modern diary.
Formula and method
Easter = the first Sunday after the church's full moon on or after March 21 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⌋; n = h + l − 7m + 114 month = ⌊n ÷ 31⌋; day = (n mod 31) + 1
Y is the year. "mod" means the remainder after dividing, and ⌊ ⌋ means round down to a whole number. Don't worry about the number of letters. Each one is a small step, and the calculator does them all for you.
The rule behind it is short. Easter is the first Sunday after the church's full moon that falls on or after March 21. The church's full moon is a full moon worked out from a fixed table, not seen in the sky. It usually lands within a day or two of the real one.
Why does the date move? The moon's phases repeat on nearly the same dates every 19 years. So a, the year's place in that 19-year cycle, sets the full moon. The values b to g are century fixes for skipped leap days and the slow drift of the moon. Then h is how many days after March 21 the full moon falls.
Next, l counts the days from that full moon to the next Sunday, minus one. The value m is almost always 0. It is 1 only in rare years, when the church table sets the full moon one day early. That pulls Easter back a week. Together these keep Western Easter between March 22 and April 25.
For Orthodox Easter, a shorter version of the same idea runs on the Julian calendar. That calendar has no century fixes, so it needs only three remainders. The calculator then adds the gap between the two calendars. That gap is 13 days from 1900 to 2099, and it grows by one day in most century years.
Worked example
When is Western Easter in 2027?
- a = 2027 mod 19 = 13. The century is b = 20 and the last two digits are c = 27.
- The century fixes are d = 5, e = 0, f = 1 and g = 6.
- h = (19 × 13 + 20 − 5 − 6 + 15) mod 30 = 271 mod 30 = 1. So the church's full moon is 1 day after March 21: Monday, March 22.
- With i = 6 and k = 3, l = (32 + 0 + 12 − 1 − 3) mod 7 = 40 mod 7 = 5. The fix-up m = ⌊134 ÷ 451⌋ = 0.
- n = 1 + 5 + 114 − 0 = 120. Then 120 ÷ 31 = 3 with 27 left over, so the month is 3 (March) and the day is 27 + 1 = 28.
Result: Western Easter 2027 is Sunday, March 28, 2027. Ash Wednesday is February 10, Palm Sunday is March 21, Good Friday is March 26 and Pentecost is May 16. Orthodox Easter that year is Sunday, May 2.
Understanding the result
Ash Wednesday, 46 days before Easter, starts Lent in Western churches. Lent is the season of preparation before Easter.
Palm Sunday is one week before Easter. Good Friday is the Friday just before it. Pentecost comes seven weeks after Easter, on a Sunday.
For Orthodox churches, Great Lent starts on Clean Monday, 48 days before Easter. Orthodox churches don't keep Ash Wednesday, so it isn't shown for that tradition.
The two traditions share the same Easter in some years, such as 2025 and 2028. From 1900 to 2099, they are otherwise one, four or five weeks apart.
Assumptions and limitations
- Dates follow the standard church tables, not the real full moon seen in the sky.
- Orthodox dates are given on today's (Gregorian) calendar, after converting from the Julian date.
- Some churches and communities set their own dates. Check locally if you need the exact day a group keeps.
- Years before 1583 and after 4099 aren't supported.
- Public holidays linked to Easter, such as Easter Monday, differ by country and aren't listed.
Frequently asked questions
What is the earliest and latest Easter can be?
Western Easter can fall from March 22 to April 25. March 22 last happened in 1818 and next comes in 2285. April 25 comes next in 2038.
Why is Orthodox Easter often later than Western Easter?
Orthodox churches use the older Julian calendar, which is now 13 days behind. Their moon table also runs a few days late. So from 1900 to 2099, Orthodox Easter is the same day, or one, four or five weeks later.
Why does the church's full moon differ from the real one?
The church uses a fixed table so everyone can agree on the date years ahead. The table follows the real moon closely, but it can be a day or two off.
Is Easter always in the same week as Passover?
No. The two are often close, because both depend on a spring full moon. But they use different rules and calendars, so they can be weeks apart.
How this calculator is checked
Method: Anonymous Gregorian algorithm (Meeus/Jones/Butcher) for Western Easter; Meeus's Julian algorithm plus the Julian–Gregorian day gap for Orthodox Easter. Both are cross-checked in tests against Gauss's Easter method for every year 1583–4099. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-26. Found a problem? Tell us.
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