Easter Date Calculator

The Easter Date Calculator computes the date of Easter Sunday for any year between 326 AD and 4099 AD, for both the Western (Gregorian) and Eastern Orthodox (Julian) traditions. Easter is one of the most mathematically complex holidays in the calendar because its date shifts each year according to a specific astronomical and ecclesiastical rule rather than falling on a fixed date.

Easter Sunday is defined as the first Sunday after the first ecclesiastical full moon that occurs on or after March 21 (the ecclesiastical spring equinox). This definition combines solar, lunar, and weekly cycles, making its calculation non-trivial. The algorithm that computes it — known as Computus, from the Latin word for calculation — has been refined over centuries.

This calculator uses the Anonymous Gregorian algorithm for Western Easter and the Julian calendar method (with Gregorian conversion) for Orthodox Easter. It also displays a full set of related holidays — from Ash Wednesday to Pentecost — derived from the Easter date.

Whether you're planning church services, calculating school holidays, or exploring historical dates, this tool provides accurate results for both major Easter traditions instantly.

The Western Easter date is computed using the Anonymous Gregorian algorithm, a series of modular arithmetic steps that together determine the month and day of Easter Sunday in any year of the Gregorian calendar.

The key difference between Western and Orthodox Easter dates lies in the calendar system each tradition uses. Western churches (Catholic and most Protestant) adopted the Gregorian calendar in 1582, which corrected drift in the Julian calendar. Orthodox churches retained the older Julian calendar for their liturgical calculations.

As a result, Orthodox Easter is calculated against the Julian calendar and then converted to the Gregorian calendar for civil dates. Because the Julian calendar drifts approximately 3 days behind the Gregorian calendar every 400 years, Orthodox Easter typically falls 1–5 weeks later than Western Easter, though in some years they coincide.

Many Christian holy days are calculated as fixed offsets from Easter Sunday. Once the Easter date is known, all of these dates follow automatically:

These offsets are the same for both Western and Orthodox traditions; they are simply applied to their respective Easter Sunday dates.

Using the Easter Date Calculator is straightforward:

1. Enter a Year: Type any year between 326 and 4099 in the Year field. The year 326 is used because that is when the Council of Nicaea standardized Easter's calculation.
2. View Results: Both Western Easter and Orthodox Easter dates appear instantly, along with all related holy days for that tradition.
3. View a Date Range: Enter a Start Year and End Year (up to 100 years apart) to see a table of Easter dates for multiple years at once. Rows highlighted in green indicate years when Western and Orthodox Easter fall on the same day.

No input format concerns — simply enter a four-digit year. The calculator handles all the complex Computus arithmetic automatically.

Calculating Easter dates has practical importance far beyond religious observance. Because Good Friday and Easter Monday are public holidays in many countries (UK, Australia, Germany, Canada, and dozens more), businesses, schools, and government agencies rely on accurate Easter dates for scheduling annual leave, academic calendars, and payroll cycles years in advance.

Software developers integrating holiday calendars into HR systems, booking platforms, and financial applications need reliable Easter date algorithms. The Computus algorithm used here is the same one implemented in most professional calendar libraries.

Historians and genealogists use Easter date calculators to interpret old documents that reference events relative to Lent, Holy Week, or Eastertide. Many historical records in Europe used Easter as a reference point for dating other events.