1. What is the Easter Date Calculation?

Easter is calculated as the first Sunday after the first full moon occurring on or after the vernal equinox (March 21). This computation follows the Gregorian calendar rules established in 1582.

2. How Does the Calculator Work?

The calculator uses the Anonymous Gregorian algorithm:

1. a = year mod 19
2. b = year div 100
3. c = year mod 100
4. d = b div 4
5. e = b mod 4
6. f = (b + 8) div 25
7. g = (b - f + 1) div 3
8. h = (19a + b - d - g + 15) mod 30
9. i = c div 4
10. k = c mod 4
11. l = (32 + 2e + 2i - h - k) mod 7
12. m = (a + 11h + 22l) div 451
13. month = (h + l - 7m + 114) div 31
14. day = ((h + l - 7m + 114) mod 31) + 1
                    

This algorithm computes the month and day of Easter Sunday for any given year in the Gregorian calendar (years 1583 and onward).

3. Importance of Easter Calculation

Details: The date of Easter determines many other important dates in the Christian liturgical calendar, including Ash Wednesday, Palm Sunday, Good Friday, Ascension Day, and Pentecost.

4. Using the Calculator

Tips: Simply enter any year between 1583 and 9999. The calculator will determine the date of Easter Sunday for that year according to Western Christian tradition.

5. Frequently Asked Questions (FAQ)

Q1: Why does Easter's date change every year?
A: Easter is based on a lunisolar calendar (combining moon phases and solar year) rather than a purely solar calendar.

Q2: What's the earliest possible Easter date?
A: March 22 (last occurred in 1818, will next occur in 2285).

Q3: What's the latest possible Easter date?
A: April 25 (last occurred in 1943, will next occur in 2038).

Q4: Do all Christians celebrate Easter on the same date?
A: No, Eastern Orthodox churches often celebrate on a different date due to using the Julian calendar for calculation.

Q5: Why does the algorithm start with year 1583?
A: 1583 was the first full year of the Gregorian calendar's implementation.