The following steps compute the date of Easter Sunday for any year ≥ 1583:
a = Y mod 19 b = Y / 100 c = Y mod 100 d = b / 4 e = b mod 4 f = (b + 8) / 25 g = (b - f + 1) / 3 h = (19a + b - d - g + 15) mod 30 i = c / 4 k = c mod 4 l = (32 + 2e + 2i - h - k) mod 7 m = (a + 11h + 22l) / 451 month = (h + l - 7m + 114) / 31 day = ((h + l - 7m + 114) mod 31) + 1
The Paschal Full Moon is approximated as March 21 + h, as per ecclesiastical rules. See more on the Paschal Full Moon.