the PFM date has always been the EFM date after March 20 (which was the equinox date in 325 A. One additional February 29 date will need to be removed in about 4140 A.
Easter Day was celebrated either: (a) on or just after the first day of the Jewish Passover (no matter on which day of the week that Easter Day occurred), or (b) on a Sunday close to or on the first Passover Day. Precise information on this subject can be found on pages 415 to 425 of the Explanatory Supplement to the 1961 Astronomical Ephemeris.
It became defined as the Sunday following the Paschal Full Moon date for the year, using a simple "19 PFM dates" table.
INDEX This procedure is a dramatic and accurate simplification of the official procedure used to calculate Easter Sunday dates, as described in Christian Prayer Books. It requires just one division on a calculator, and three simple additions.
Paschal Full Moon dates are copied directly from these Books. This procedure appears more compactly in the 1988 Australian Almanac (titled "The Dating of Easter") held in the Canberra Library, Australia.
There are three steps to calculating the Easter Sunday date: Find the Easter Sunday date from Table E Table A below shows PFM dates for years 326 to 2599 A. If you're looking further into the future, click here to see another Table A for years 2600 to 4099 A. Use the total result from step 2 to find the day of week of the PFM date in Table E, then add the number of days shown to the PFM date to find the Easter Sunday date.