Holy days · 3 min read
Why Orthodox Easter often falls on a different date
Understand Julian and Gregorian Easter calculations, ecclesiastical full moons and why modern Passover is not an extra universal rule.
The difference is in the calculation
Many Eastern Orthodox churches and Western churches celebrate Easter on different dates because they use different calendar and lunar-table conventions to determine it. They can also celebrate on the same date. The difference does not mean they are commemorating unrelated events: both celebrate Christ's resurrection. [1][2]
The important question is not simply which calendar a church uses for every ordinary date. Ask which paschal calculation it follows. A short explanation of the calculation is more useful than assuming that a church's entire calendar can be inferred from the date of one feast.
The full moon is an ecclesiastical one
The usual rule places Easter on the Sunday after the first ecclesiastical full moon falling on or after March 21, the calendar's fixed spring equinox. The relevant March 21 and lunar tables belong to the calculation being used. They are not simply the exact astronomical equinox and an observed full moon. [2]
That distinction explains why checking a weather app's moon phase is not enough to reproduce the church date. An astronomical event and a tabular calendar marker can be related without being identical. Use a source that states which system it is calculating.
Julian and Gregorian conventions
The Gregorian and older Julian approaches use different calendar conventions and lunar tables. Their results can therefore map to different dates in the civil calendar. The World Council of Churches' Aleppo document explains the calculation problem in the context of efforts toward a common Easter date. [2][1]
The Gregorian reform of 1582 changed the Western calendar and Easter tables. Most Eastern churches retained the older paschal calculation. Some Orthodox churches later changed the calendars used for fixed-date feasts while keeping their Easter calculation tied to the Julian system. A Christmas date therefore does not automatically reveal how a church dates Easter. [1][2]
Must Orthodox Easter wait until Passover ends?
The common claim that Orthodox Easter must always occur after the end of modern Jewish Passover is misleading. The Orthodox Church in America's discussion explains that independence from Jewish calendar reckoning did not forbid accidental coincidence. The WCC document likewise distinguishes the traditional Christian calculation from dependence on contemporary Jewish reckoning. [3][1]
Historical connections between Easter and Passover are not the same thing as an additional modern rule requiring a reader to wait for Passover to finish. Keeping those ideas separate avoids a popular explanation that cannot accurately account for the calendar history.
How to check a date accurately
Name the year and church or jurisdiction you are checking. Confirm the civil date with its published calendar, and distinguish a general explanation from a local announcement about services. A feast date does not by itself provide the time of every associated service.
If two calendars agree in a given year, that agreement is compatible with different calculation systems. If they differ, explain the conventions before assigning theological meaning to the gap. The calendars are evidence about how the date is determined, not a shortcut to all the differences between the churches.
Sources & further reading
The numbered links connect claims to the sources below. Sources checked October 13, 2026 by a separate AI fact-checking agent. This is not human or specialist review. Read our editorial approach.
- Towards a Common Date for Easter ↗World Council of Churches / Middle East Council of Churches · Accessed October 13, 2026
- The Date of Easter ↗U.S. Naval Observatory · Accessed October 13, 2026
- Concerning the Date of Pascha and the 1st Ecumenical Council ↗Orthodox Church in America · Accessed October 13, 2026
Found a problem? Send a correction with the passage and a supporting source.
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