How the Date of Easter Is Determined Each Year

As we enter spring and approach one of the most important holidays in Christianity—Easter—it’s time to dig through your calendar to ensure you have the right date circled. After all, Easter has probably one of the most unique ways of determining its date of any religious holiday and it’s not always obvious when we’ll be celebrating Easter each year.

In 2022, Easter was on April 17. This year (2023) Easter will be on April 9. Next year, in 2024, it will be on March 31. Huh? What gives?

For years I’ve been intrigued by this. For most holidays there is a fairly simple method for determining the date: Christmas is always on December 25th. Mother’s Day is always the second Sunday in May. Labor Day is always the first Monday in September. Easter, however, isn’t quite that simple.

So, when exactly does occur each year? And how is it decided?

Easter Comes on the first Sunday after the first full moon after the spring equinox.

Since I like to make visuals, here’ one to help you remember:

If the method for deciding when to celebrate Easter is as confusing to you as it has been me, it’s worth looking a littler deeper to understand how this works. Let’s look at the these three factors more closely.

First things, first though. To make matters even more confusing, it’s important to know that Orthodox Christians and Christians follow different ecclesiastical calendars—so they celebrate on Easter different days each year. Orthodox Christians use the Julian calendar, which was developed by Julius Caesar in 45 B.C. and observed the Easter holiday between April 4 and May 8. The rest of Christianity typically uses the Gregorian calendar, which celebrates Easter between March 22 and April 25. For the rest of this post, I’ll be talking about the Gregorian calendar, which is typically used by the majority of Christians in Western countries and cultures.

Easter is always on Sunday.

In Christianity, Sunday is recognized as the Sabbath, or the holy day each week when religious services and sacred observances are typically held. Early Christians after the death of Jesus Christ began the tradition of celebrating Easter (which commemorates Christ’s resurrection) on Sunday, a day when they traditionally worshipped. While the exact Sunday in which it was observed was inconsistent, Sunday observance of Easter became a standardized norm almost immediately.

Deciding which Sunday was often a point of debate so, in 325 A.D., the Council of Nicea determined to standardize it. Making Easter the first Sunday after the first full moon after the spring equinox was settled on as the determining factor. By the 8th Century A.D., this method had become almost universally accepted.

Easter follows a full moon, but is never on the same day as a full moon.

According to the Bible, Jesus’ death and resurrection occurred at the time of the Jewish Passover, which was celebrated on the first full moon after the vernal (spring) equinox. Thus, tradition holds the commemoration of Christ’s resurrection must happen after the first full moon, never on it.

Easter cannot come before March 22 and it’s never after April 25.

The spring equinox, which signals the first day of spring, is the day each year where the sun’s rays hit the earth’s equator in such a way that the earth is neither tilted toward or away from the sun. Interestingly, this causes nearly everywhere on earth to have 12 hours of sun and 12 hours of darkness.

In the United States, the official spring equinox typically happens in the afternoon on March 20. However, with different time zones across the world, the spring equinox actually occurs a day later, on March 21, in countries like China. So, to be consistent globally, the “ecclesiastical” spring equinox is recognized as March 21, the latest possible date when the equinox occurs. Thus, the soonest Easter can be is on March 22, the day after the ecclesiastical equinox.

Because of how the lunar cycle works, there is a full moon every 29.5 days. Thus, if a full moon occurred at its latest on the date of the spring equinox (March 21), and if that date were a Sunday, it would take 29 days to reach the next full moon (which would be April 19 and a Monday) and another six days to get to Sunday, which would be April 25.

As a point of curiosity, Easter hasn’t occurred that late since 1943. And it won’t happen that late again until 2038.

Final Thoughts

Of course, none of this is as important as the meaning of the holiday itself. Finding a date that Christians agree on helps with creating a global commemoration of Christianity’s most important day, but it all seems symbolic anyway. Whether you follow the Julian calendar, the Gregorian calendar, or another established method for when to celebrate Easter—like in the UK, where the government once created the Easter Act of 1928, which established Easter to be on a Sunday between April 9 and April 15 each year—I hope you’re able to now know at least how the large majority of Christians decide on the date!