Pascha falls on the first Sunday after the first full moon following the vernal equinox. That’s the short answer, but there’s more to it than that.
The First Ecumenical Council at Nicea in 325 AD established this formula. The bishops wanted two things: unity across all the churches and a clear relationship to the Jewish Passover. Christ rose on the Sunday after Passover, so our celebration needed to honor that timing. But the Council also wanted the Church to calculate the date independently rather than relying on Jewish communities to announce when Passover would fall.
Here’s where it gets specific. We’re not talking about the astronomical full moon you’d see if you walked outside and looked up. The Church uses what’s called the ecclesiastical full moon, calculated according to a 19-year cycle that was already ancient when Nicea adopted it. And the vernal equinox isn’t the actual moment when day and night are equal length. It’s fixed at March 21.
March 21 on which calendar? That’s the question that causes all the confusion.
The Orthodox Church still uses the Julian calendar for calculating Pascha. That was the calendar in use when the Council of Nicea met, and we’ve kept it. The Western churches switched to the Gregorian calendar in 1582, which corrected the Julian calendar’s slight drift. By now, the Julian calendar is 13 days behind the Gregorian. So when we say March 21, we mean what the rest of the world calls April 3.
This means Orthodox Pascha can never fall before April 3 on the civil calendar. It also means we’re often celebrating on a different Sunday than our Catholic and Protestant neighbors. Sometimes the dates align. Sometimes we’re a week apart. Sometimes five weeks.
There’s one more rule. Pascha can’t fall on the same day as Jewish Passover, and it can’t come before Passover. We celebrate after, as Christ rose after the Passover meal. This matters because the Jewish calendar is lunar, so Passover moves around too. When you combine the Julian calendar’s March 21 equinox with the requirement to follow Passover, you get dates that can range from April 4 to May 8 on the civil calendar.
I know this sounds complicated. People in Beaumont ask me every year why we can’t just pick a date and stick with it, or why we can’t celebrate Easter with everyone else. The answer is that we’re being faithful to what the whole Church agreed on in 325. We’re not trying to be difficult. We’re trying to be consistent with how Christians have celebrated the Resurrection for seventeen centuries.
The Antiochian Archdiocese has published detailed explanations of this, and they’re clear: we follow the ancient practice because it connects us to the Church’s unbroken tradition. When you’re standing in St. Michael’s for the Paschal vigil at midnight, you’re celebrating on a date calculated the same way Christians in Antioch calculated it in the fourth century. That continuity matters.
Does it feel strange to celebrate alone sometimes, when your Baptist coworkers already had their Easter egg hunt three weeks ago? Sure. But there’s something powerful about keeping the ancient rhythm, even when it sets us apart. The calendar isn’t arbitrary. It’s rooted in the Passover, in the Council’s wisdom, in the Church’s memory of how Christ’s death and Resurrection actually unfolded in time.
If you want to know when Pascha falls in any given year, you can find paschal tables that list the dates decades in advance. Or you can just check the church calendar each January. The date moves, but the formula doesn’t. First Sunday after the first full moon after March 21 Julian. Every year. Just like Nicea said.
