A Perpetual Easter and Passover Calculator

Introduction

click for a larger image — Easter Sunday commemorates the ressurection of Christ which occurred three days after his crucifixion. The date of Easter Sunday, governed by the calendrical cycles of the Sun and the Moon, is one of the most important dates in the Christian liturgical calendar as it determines the dates of the various days which belong to the annual Easter cycle. Manuscript leaf from a French missal (dated c.1270-1280) in the Metropolitan Museum of Art (New York),

Quand Georges Dieu crucifera
Que Marc le ressucitera
Et que Saint Jean le portera
La fin du monde arrivera.

French calendar riddle often erroneously attributed to Michel de Nostredame (1503-1566)

The JavaScript calculators on these web pages provide the calendar dates of Easter Sunday according to the various Julian Easter reckonings and the Gregorian Easter reckoning as well as the first day of the Jewish Passover feast (15 Nisan) according to the present-day rabbinical calendar reckoning.

Also provided is a web page with an overview of the feast days in the Christian liturgical year and various other web pages comparing the dates of Easter according to different modes of calculation.

The Julian Easter reckoning was used generally up to 1582 when a modified algorithm was introduced with the Gregorian calendar reform. However, in many protestant countries the change to the Gregorian calendar and corrected Easter reckoning was not implemented until well into the 18th or even the 19th century. The Julian Easter reckoning is still employed by the Greek, Russian, Coptic and Ethiopian Orthodox churches.