How Do We Determine When To Celebrate Easter?
Easter occurs on the first Sunday after the first full moon that occurs on or after the Spring equinox in the northern hemisphere. The equinox is when the length of day and night are equal due to the tilt in the earth’s axis and its position in its orbit around the sun. The equinox usually occurs on March 21st but can occur on March 20th or even March 19th in leap years. However, the Council of Nicaea in 325AD decided to use March 21st as the equinox date for calculating when Easter falls, and it came up with the formula described above.
If the full moon happens on Saturday, March 21st, the next day, Sunday, will be Easter. That makes March 22nd the earliest date for Easter. If the full moon occurred on March 20th, the next full moon would be 29 days later or April 18th. Easter would be the following Sunday or April 25th if that was a Sunday. That makes the range of possible dates for Easter, based on the Council of Nicaea formula, from March 22nd to April 25th.
You might ask why the Council of Nicaea decided to set the date to celebrate Easter that way. From the accounts in the bible, we know that Jesus went to Jerusalem for Passover. The Last Supper was a Passover-related meal, not a Seder meal, as that tradition did not exist until after the destruction of the temple in 70AD. The Gospels of Matthew (26:17-30), Mark (Mark 14:12-2), and Luke (Luke 22:7-30) imply that the last supper occurred on the night of Passover, “the first day of Unleavened Bread.” The Gospel of John (13:1-38) implies that the Last Supper occurred before the feast of Passover. Jesus was arrested that night and was crucified the next day. Then he was resurrected on the third day, which the bible tells us, in all four gospels, was the first day of the week, or Sunday. Working backward, that puts the crucifixion on Friday and the last supper on Thursday.
Passover commemorates the Israelites’ liberation from slavery and the exodus from Egypt. God sent a series of plagues to Egypt to convince the Pharaoh to let the Israelites go. The tenth and final plague struck down all the firstborn people and livestock except those who put the blood of a sacrificed lamb on their lintel and doorposts. Those houses were passed over, and the firstborns were spared. They were also directed to eat unleavened bread from the fourteenth day of the month to the twenty-first day of the month (see Exodus 12). The date of Passover is based on the Hebrew calendar, which is based on lunar cycles. Specifically, it is on the 15th day of the Hebrew month of Nisan and is celebrated for eight days, corresponding to the time the Israelites were told to eat no leavened bread. Given that there are not an even number of lunar cycles in a year, the Passover occurs on different dates and days of the week in various years, from March 26th to April 25th.
The Council of Nicaea was faced with competing criteria for when to celebrate Easter. They could have set the date based on the date of Passover and not worried about the day of the week. However, we understand that the Roman Emperor Constantine did not want to tie Easter to the Jewish holiday of Passover. Also, the Bishops wanted to celebrate Easter on a Sunday because the scriptures tell us that it occurred on that day of the week. The Eastern churches did not want to abandon the relationship with the lunar cycles. So, they came up with a formula that assures Easter is celebrated on a Sunday, is based on the equinox and lunar cycles, and is in the same general time frame as Passover but not based on Passover.
The Eastern Orthodox church uses the same formula but is based on the less accurate Julian calendar, which has drifted thirteen days compared to the Gregorian calendar, resulting in Easter occurring between April 4th and May 8th.
You might also ask, what was the date on the Gregorian calendar that Jesus was resurrected in the year he was crucified? There are several issues in determining that. First, we do not know which year Jesus was crucified. It is generally placed in the range 28AD to 36AD. Second, the Roman Empire used the Julian calendar at the time, which did not correctly account for the actual length of a year (365.2422 days), so it drifted over time. The Gregorian calendar that we use today accounts for that better. As you might expect, many scholars have tried to work backward and calculate when Passover was in those years to figure out which year works best with what we know from the Bible to determine the date of the crucifixion on the Gregorian calendar. Further complicating the issue is that a “day” was viewed as starting at sundown, not midnight, back then. So, what we call Wednesday evening is Thursday in that system. Some scholars assert that when the bible says Jesus was resurrected on the third day, that means three 24-hour days later or 72 hours, and others say partial days count in the three days. All this leads scholars to different conclusions about what day of the week the last supper and the crucifixion occurred and which year fits what we know or can deduce from lunar cycles as to when Passover was celebrated in those years.
The most widely accepted theories today, based on the calculations about when Passover occurred, are that the crucifixion occurred in the year 33AD or the year 30AD. However, there are strong proponents of the years 28AD, 31AD, and 32AD. From my reading, the most widely accepted year is 33AD, with the crucifixion occurring on Friday, April 3rd, meaning Easter would be April 5th. Those who propose it was in the year 30AD place the crucifixion as occurring on Friday, April 7th, meaning Easter would be April 9th. While interesting, these are theories; we cannot be certain.
There have been recent proposals to come to a common way of calculating the date of Easter in Eastern and Western traditions. One such proposal is the second Sunday in April. However, the Christian world has yet to agree on a new formula. In 2025, Easter is celebrated on April 20th in both the Eastern and Western traditions; this happens on average every three or four years. It last occurred in 2010, 2011, 2014, and 2017 and will happen again in 2028 and 2031.
Summary
We do not know for sure what year that Jesus was crucified and resurrected. Most scholars place it in 33AD or 30AD, but other years are also proposed. There is disagreement about when Passover was celebrated in those years, but the most common theories place the crucifixion on Friday, April 3rd, 33AD, or Friday, April 7th, 30AD.
The Bible makes it clear that the resurrection occurred on a Sunday, a few days after the start of Passover, but it does not tell us the year. When deciding when to celebrate the resurrection today, is it more important that it be on the same day of the month that it occurred, the same day of the week that it occurred, the same relationship to the lunar cycle or the equinox, or related to when Passover occurs? No date fits all those criteria and different people have different opinions on which criteria is most important, so there is no obvious correct answer.
Today, most Christians celebrate Easter based on the formula that was decided in 325 AD at the Council of Niciea, knowing that the date we choose to celebrate Easter is not as important as what Christ did for us or that we remember His sacrifice and resurrection.
Douglas A. Leas, April 2025
Sources:
I read many articles about this topic to create this summary; here are just a few of them:
Akin, Jimmy, 2024, “The Accurate Date of the Crucifixion”, Catholic Answers, Retrieved April 10, 2025
Akin, Jimmy, 2020, “7 Clues Tell Us *Precisely* When Jesus Died (the Year, Month, Day and Hour Revealed)”, National Catholic Register, Retrieved April 11, 2025.
Bible Study Manuals, “The Crucifixion And Resurrection Of Christ: Chronology Of Events”, Retrieved April 11, 2025.
Encyclopaedia Romana, 2025, “The Death of Jesus”, Retrieved April 10, 2025
Lilleby, Jan, “What Day of the Week Was Jesus CRUCIFIED?”, Retrieved April 10, 2025 (Concludes Wednesday the 28th of April 28 AD)
Köstenberger, Andreas, 2014, “April 3, AD 33: Why We Believe We Can Know the Exact Date Jesus Died”, Center For Biblical Studies and Midwestern Seminary, Retrieved April 10, 2025
Robinson, Rich, 2017, "Was Jesus’ Last Supper a Passover Seder?”, Retrieved April 12, 2025
Vega, Luis, Crucifixion Evidence 32 AD, PostScripts Publications, ISBN: 978-1-312-48228-9
Wikipedia, Chronology of Jesus,Retrieved April 11, 2025.