Orthodox Pascha falls on a different Sunday than Western Easter because we use a different calendar and follow different rules for calculating the date. Sometimes the dates coincide. Often they don’t.
The difference comes down to two things: which calendar you use and which mathematical formula you follow. Western churches switched to the Gregorian calendar in 1582 and adjusted their Easter calculation accordingly. Orthodox churches kept the traditional method tied to the Julian calendar and the ancient paschal tables handed down from the Fathers.
The Calendar Question
Most Orthodox churches calculate Pascha using the Julian calendar, which runs thirteen days behind the Gregorian calendar that civil society uses. That gap grows to fourteen days after 2100. When we say the vernal equinox falls on March 21st, we mean March 21st on the Julian calendar, which lands on April 3rd on your phone’s calendar. Western churches use March 21st Gregorian as their baseline.
This isn’t stubbornness. It’s continuity with the Church’s received practice.
The Rules That Matter
The First Ecumenical Council at Nicea in 325 established the principles. Pascha must fall on the Sunday following the first full moon after the vernal equinox. All Christians should celebrate on the same day. And the Church’s calculation should be independent, not dependent on Jewish calendar computations.
But here’s where it gets specific. The Orthodox Church uses what’s called the Paschalion, a set of tables and rules developed in Alexandria that approximate the full moon using a nineteen-year cycle. These are ecclesiastical calculations, not astronomical observations. The “full moon” in the Paschalion isn’t necessarily the actual full moon you see rising over the refineries on I-10. It’s a liturgical full moon, calculated according to ancient mathematical patterns.
Western churches adapted their formula when they adopted the Gregorian calendar. We didn’t.
Why We Haven’t Changed
You might wonder why Orthodox churches don’t just switch to make things simpler. There was actually discussion about this at a pan-Orthodox congress in Constantinople in 1923. Some churches adopted a revised Julian calendar for fixed feasts like Christmas. But Pascha stayed on the old calculation.
The reason isn’t nostalgia. It’s about maintaining the link to Nicea and the Fathers. Changing how we calculate Pascha isn’t a minor calendrical adjustment. It’s an ecclesial decision with canonical weight. The Church received this method from the councils and the tradition. We don’t change it unilaterally because it would be more convenient for interfaith potlucks.
There’s also a theological dimension. Pascha is the Feast of Feasts, the hinge of the entire liturgical year. Everything in the church calendar pivots around it. The fifty days of Pentecost, the Apostles’ Fast, the beginning of Great Lent, all of it flows from Pascha’s date. The Church measures time by her own rhythm, not by civil calendars or modern astronomical calculations.
When They Line Up
Some years both Easters fall on the same Sunday. This happens when the Julian-based and Gregorian-based calculations happen to produce the same civil date. It’s not rare, but it’s not the norm either. Whether they coincide depends on how the lunar cycle and the weekday pattern align in any given year.
When they differ, Orthodox Pascha usually comes later, sometimes by a week, sometimes by five weeks. In 2025, for instance, Western Easter falls on April 20th while Orthodox Pascha is April 20th, they coincide. But in 2024 they were five weeks apart.
You can find the dates years in advance because the Paschalion is a fixed system. Nothing changes year to year in the formula itself.
What This Means for You
If you’re inquiring into Orthodoxy and your family celebrates Easter in April while we’re still in Lent, that can feel strange. You’ll be fasting while they’re eating ham. Or you’ll be celebrating the Resurrection a month after your Baptist grandmother already had her Easter service.
It’s one of those visible differences that marks Orthodox life as distinct. Not better, not worse, just different in a way that connects us to something older than the Reformation, older than the medieval papacy, older than the split between East and West. When we celebrate Pascha according to the ancient calculation, we’re doing what the Church in Antioch and Alexandria and Constantinople did fifteen hundred years ago.
Fr. Thomas Hopko used to say that the Church keeps her own time. That’s what this is about. We don’t let civil calendars or secular convenience dictate when we celebrate the Resurrection. We follow the rhythm the Church received and has kept.
If you want to understand the actual math behind it, the OCA has a detailed statement on the Paschalion and the Nicene principles. But the short version is this: we calculate Pascha the way the Church always has, and we’ll keep doing it that way until an ecumenical council says otherwise.
