How Are Easter’s Dates Calculated?

Today April 20th, Easter Sunday. Easter can fall anytime between March 22nd and April 25th. Have you ever wondered why?

Some of our holidays, like Christmas, are celebrated on the same day each year, while others follow a different set of standards. The leaders of the early church determined Easter needed to be celebrated on Sunday each year, and rightly so. In the early days, it was set on the Sunday following the first astronomical full moon after the spring equinox.

Then in 325 AD, the Council of Nicea decided they needed to establish a more standardized system for determining the date. Astronomers were able to approximate the dates of the full moons in future years, and established a table of ecclesiastical full moon dates. These dates would be the basis for setting holy days on the ecclesiastical calendar.

According to Mary Fairchild, in her article “Why Does the Date for Easter Change Each Year,” she writes, “At the heart of the matter lies a very simple explanation. The early church fathers wished to keep the observance of Easter in correlation to the Jewish Passover. Because the death, burial, and resurrection of Jesus Christ happened after the Passover, they wanted Easter to always be celebrated subsequent to the Passover. And, since the Jewish holiday calendar is based on solar and lunar cycles, each feast day is movable, with dates shifting from year to year.”

By 1583 AD the table for calculating the ecclesiastical full moon dates was established and been used ever since. According to the tables, the Paschal, or Passover, full moon is the first ecclesiastical full moon after March 20, which was the spring equinox date in 325 AD.

The early leaders were mindful of the best way to set Easter’s date, and I commend them. Calculating it is not as complicated as I’d once thought. Happy Easter.

Christine Husom is the author of the Winnebago County Mystery Series.


Filed under How To

2 responses to “How Are Easter’s Dates Calculated?

  1. Interesting. Thanks for the enlightenment, Christine.

  2. I kind of like not having a fixed date for Easter too. And I’m sure I read somewhere that the Easter and Western calculations coincided this year.

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