How is Easter Sunday calculated

So you can always calculate the date of the holidays around Easter

  • Do you ask yourself the same questions every year?
  • When is Shrove Monday, when does Lent begin and how is the date for Easter, Pentecost or Ascension Day calculated?
  • We'll explain it to you.

You can find more topics about Easter here

Many holidays are postponed every year. But why? Easter is dependent on the full moon, Rose Monday is calculated after Easter. We explain to you how the data is created.

Calculate Rose Monday, Whitsun and Co.: Everything depends on Easter

Easter Sunday is always the first Sunday after the first full moon after the beginning of spring on March 21st.

Once you have found this date, you only have to count back 48 days and you have the date for Rose Monday. The earliest possible date for Easter is March 22nd, the latest possible April 25th.

Easter Sunday is also the basis for all other movable holidays of the year, for example Ascension Day and Pentecost. The Ascension Day, which is also the German date for Father's Day, follows 40 days after Easter, which means that it always falls on a Thursday.

The date for Pentecost is also determined after Easter Sunday. Since Pentecost has to take place 50 days after Easter, it always falls on a Monday.

Calculate Easter with the Gaussian Easter formula

The German mathematician Carl Friedrich Gauß also dealt with the phenomenon of the Easter calculation and developed a formula that enables a calculation. Although this works without any lunar cycles, it is not that easy to remember.

Gauss uses the so-called modulo calculation (abbreviated "mod"), a function that describes the remainder of a division from two whole numbers.

Example: 10 mod 3 = 1, since 9 is the largest possible number that can be divided by 3 and 10 - 9 = 1

The Easter formula from Carl Friedrich Gauß

The existing data from 2020 was used as an example calculation.

First you have to divide the year by 19:

2020/19 = 106, 6 remaining

This remainder is called a, i.e. a = 6

Next, divide the year by 4; the rest is called b:

2020/4 = 505, what remains is b = 0

Then divide the year by 7 and call the remainder c:

2020/7 = 288, what remains is c = 4

Now a is multiplied by 19 and 24 is added. The result is divided by 30. The remainder in this case is called d:

6 * 19 = 114

114 + 24 = 138

138/30 = 4, the remainder d is 18

Now multiply b by 2, c by 4 and d by 6, add everything up and then add 5. The result is divided by 7 and the remainder is called e.

(0 * 2) + (4 * 4) + (18 * 6) + 5 = 129

129/7 = 18, the remainder e is 3

If you add the values ​​d and e to the number 22, you get the date of Easter Sunday:

22 + 18 + 3 = 43

However, as is well known, March only has 31 days - everything that goes beyond 31 is already in April:

43 - 31 = 12

So Easter Sunday 2020 is April 12th.

The dates for Easter, Whitsun & Co. for the year 2021

According to the calculation of the Gaussian Easter formula, Easter Sunday falls on April 4th this year. Rose Monday is 48 days ago and falls on February 15th. Ascension Day comes 40 days after Easter Sunday, i.e. May 13th and Pentecost exactly ten days later, on Monday, May 23rd.