The Julian calendar date Thursday October 4, 1582 was followed by the Gregorian calendar date Friday October 15, 1582. Consequently, their Easter Sunday dates are identical up to 1582, then from 1583 onwards often differ from those of Western churches.
In some years the Orthodox Easter Sunday occurs on the same day as the Western Easter Sunday.
This replacement did not occur until later in many countries e.g. See GM Arts Easter Date Calculations for more information.
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.
For example, year 2285 gave us a PFM date of March 21, and step 2 gave us a total result of 6.
The present method describing the Easter Dating Procedure can be found in Christian Prayer Books.
This procedure has been dramatically simplified by Ronald W. See Finding Easter Sunday Dates with a Calculator for a clear and unique explanation of this procedure.
Easter Sunday date was based on the Julian calendar in use at that time.
Despite frequent references to March 21, this date has no special significance to any recent Easter dating methods.
The example for year 1995 gives the Julian Easter Sunday date of April 10, and Table F shows that we need to add 13 days to convert it to the Gregorian calendar date of April 23.
This date is the Gregorian calendar Orthodox Easter Sunday date for year 1995 A. Other examples: Year 1994: Step 1: PFM=A17, Step 2: 1 0 5 = 6, Step 3: A17 1=Julian April 18, 1994, Step 4: Julian A18 13 = Gregorian May 1, 1994 Year 2870: Step 1: PFM=M25, Step 2: 6 5 3 = 14, Step 3: M25 7=Julian April 1, 2870, Step 4: Julian A1 19 = Gregorian April 20, 2870 INDEX Here is an algorithm written in BASIC to calculate the Gregorian Easter Sunday date for years 1583 to 4099 (Western churches only).
To determine the Orthodox Easter Sunday date, it is first necessary to find the Julian Easter Sunday date, then to add the number of days which have been "skipped" in the Gregorian calendar.