Easter and holidays related to it are
moveable feasts, in that they do not fall on a fixed date in the
Gregorian or
Julian calendars (both of which follow the cycle of the sun and the seasons). Instead, the date for Easter is determined on a
lunisolar calendar similar to the
Hebrew calendar.
Early Church controversies icon depicting the Easter story.
Eastern Orthodox Christians use a different computation for the date of Easter from the Western churches. The precise date of Easter has at times been a matter of contention. By the later 2nd century, it was widely accepted that the celebration of the holiday was a practice of the
disciples and an undisputed tradition. The
Quartodeciman controversy, the first of several
Easter controversies, arose concerning the date on which the holiday should be celebrated. The term "Quartodeciman" refers to the practice of ending the Lenten fast on
Nisan 14 of the
Hebrew calendar, "the 's passover". According to the church historian
Eusebius, the Quartodeciman
Polycarp (bishop of
Smyrna, by tradition a disciple of
John the Apostle) debated the question with
Anicetus (bishop of Rome). The
Roman province of Asia was Quartodeciman, while the Roman and Alexandrian churches continued the fast until the Sunday following (the Sunday of
Unleavened Bread), wishing to associate Easter with Sunday. Neither Polycarp nor Anicetus persuaded the other, but they did not consider the matter
schismatic either, parting in peace and leaving the question unsettled. Controversy arose when
Victor, bishop of Rome a generation after Anicetus, attempted to
excommunicate Polycrates of Ephesus and all other bishops of Asia for their Quartodecimanism. According to Eusebius, a number of synods were convened to deal with the controversy, which he regarded as all ruling in support of Easter on Sunday. Polycrates (), however, wrote to Victor defending the antiquity of Asian Quartodecimanism. Victor's attempted excommunication was apparently rescinded, and the two sides reconciled upon the intervention of bishop
Irenaeus and others, who reminded Victor of the tolerant precedent of Anicetus. Quartodecimanism seems to have lingered into the 4th century, when
Socrates of Constantinople recorded that some Quartodecimans were deprived of their churches by
John Chrysostom and that some were harassed by
Nestorius. It is not known how long the Nisan 14 practice continued. But both those who followed the Nisan 14 custom, and those who set Easter to the following Sunday, had in common the custom of consulting their Jewish neighbors to learn when the month of Nisan would fall, and setting their festival accordingly. By the later 3rd century, however, some Christians began to express dissatisfaction with the custom of relying on the Jewish community to determine the date of Easter. The chief complaint was that the Jewish communities sometimes erred in setting Passover to fall before the
Northern Hemisphere spring equinox. The
Sardica paschal table confirms these complaints, for it indicates that the Jews of some eastern Mediterranean city (possibly
Antioch) fixed Nisan 14 on dates well before the spring equinox on multiple occasions. Because of this dissatisfaction with reliance on the Jewish calendar, some Christians began to experiment with independent computations. Others, however, believed that the customary practice of consulting Jews should continue, even if the Jewish computations were in error.
First Council of Nicaea (325 AD) , with Arius depicted as defeated by the council, lying under the feet of
Emperor Constantine The settlement of the
controversy about the Paschal season caused by the
Quartodeciman practice of Asian
churches is listed in our principal source for the works of the
Council of Nicaea,
Socrates Scholasticus's
Ecclesiastical History, as one of the two reasons for which emperor
Constantine convened the Council in 325. The Canons of the Council preserved by
Dionysius Exiguus and his successors do not include any relevant provision, but letters of individuals present at the Council mention a decision prohibiting Quartodecimanism and requiring that all Christians adopt a common method to independently determine Paschal observance following the churches of Rome and Alexandria, the latter "since
there was among the Egyptians an ancient science for the computation." Already in the end of the 4th century and, later on,
Dionysius Exiguus and others following him maintained that the bishops assembled at Nicaea had promulgated the celebration of Easter on the first Sunday after the first full moon on or after the vernal equinox and that they had adopted the use of the 19-year lunar cycle, better known as
Metonic cycle, to determine the date; subsequent scholarship has refuted this tradition, but, with regards to the rule of the equinox, evidence that the church of Alexandria had implemented it before 325 suggests that the Council of Nicaea implicitly endorsed it. Canons and sermons condemning the custom of computing Easter's date based on the Jewish calendar indicate that this custom (called "protopaschite" by historians) did not die out at once, but persisted for a time after the Council of Nicaea. In any case, in the years following the council, the computational system that was worked out by the church of Alexandria came to be normative. The Alexandrian system, however, was not immediately adopted throughout Christian Europe. Following
Augustalis' treatise (On the Measurement of Easter), Rome retired the earlier
8-year cycle in favor of Augustalis' 84-year
lunisolar calendar cycle, which it used until 457. It then switched to
Victorius of Aquitaine's adaptation of the Alexandrian system. Because this Victorian cycle differed from the unmodified Alexandrian cycle in the dates of some of the Paschal full moons, and because it tried to respect the Roman custom of fixing Easter to the Sunday in the week of the 16th to the 22nd of the lunar month (rather than the 15th to the 21st as at Alexandria), by providing alternative "Latin" and "Greek" dates in some years, occasional differences in the date of Easter as fixed by Alexandrian rules continued. Early Christians in Britain and Ireland also used an 84-year cycle. From the 5th century onward this cycle set its equinox to 25 March and fixed Easter to the Sunday falling in the 14th to the 20th of the lunar month inclusive. This 84-year cycle was replaced by the Alexandrian method in the course of the 7th and 8th centuries. Churches in western continental Europe used a late Roman method until the late 8th century during the reign of
Charlemagne, when they finally adopted the Alexandrian method. Since 1582, when the
Roman Catholic Church adopted the Gregorian calendar while most of Europe used the Julian calendar, the date on which Easter is celebrated has again differed.
Computations , Italy. Five 19-year cycles are represented as concentric circles. Dates are given using the system of the
Roman calendar, as well as the day of the lunar month. In 725,
Bede succinctly wrote: "The Sunday following the full Moon which falls on or after the
equinox will give the lawful Easter." However, this does not precisely reflect the ecclesiastical rules. The full moon referred to (called the
Paschal full moon) is not an astronomical full moon, but the
14th day of a
lunar month. Another difference is that the
astronomical equinox is a natural astronomical phenomenon, which can fall on 19, 20, or 21 March, while the ecclesiastical date is fixed by convention on 21 March. In addition, the lunar tables of the Julian calendar are currently five days behind those of the Gregorian calendar. Therefore, the Julian computation of the Paschal full moon is a full five days later than the astronomical full moon. The result of this combination of solar and lunar discrepancies is divergence in the date of Easter in most years (see table). Easter is determined on the basis of
lunisolar cycles. The lunar year consists of 30-day and 29-day lunar months, generally alternating, with an
embolismic month added periodically to bring the lunar cycle into line with the solar cycle. In each solar year (1 January to 31 December inclusive), the lunar month beginning with an
ecclesiastical new moon falling in the 29-day period from 8 March to 5 April inclusive is designated as the paschal lunar month for that year. Easter is the third Sunday in the paschal lunar month, or, in other words, the Sunday after the paschal lunar month's 14th day. The 14th of the paschal lunar month is designated by convention as the
Paschal full moon, although the 14th of the lunar month may differ from the date of the astronomical full moon by up to two days. and has been adopted by almost all Western Christians and by Western countries which celebrate national holidays at Easter. For the British Empire and colonies, a determination of the date of Easter Sunday using
Golden Numbers and
Sunday letters was defined by the
Calendar (New Style) Act 1750 with its Annexe. This was designed to match exactly the Gregorian calculation.
Western–Eastern divergence In Western Christianity, using the Gregorian calendar, Easter always falls on a Sunday between 22 March and 25 April, within about seven days after the astronomical full moon. The preceding Friday,
Good Friday, and following Monday,
Easter Monday, are
legal holidays in many countries with predominantly Christian traditions.
Eastern Orthodox Christians use the same rule but base their 21 March according to the
Julian calendar. Because of the thirteen-day difference between the calendars from 1900 through 2099, 21 March Julian corresponds to 3 April in the Gregorian calendar (during the 20th and 21st centuries). Consequently, the date of Orthodox Easter varies between 4 April and 8 May in the Gregorian calendar. Furthermore, because the lunar tables of the Julian calendar are five days behind astronomical reality, the full moon, as defined by the Eastern Orthodox Church, is five days later, on a day which actually is a waning gibbous moon. Therefore, if a Sunday falls on any of the four days after the astronomical full moon, this is regarded as occurring before the ecclesiastical full moon and Easter Sunday will be a week later. As a result, Orthodox Easter may fall on the same day as Catholic Easter, a week later, four weeks later, or five weeks later (but at no other time intervals, at least until the 25th century). Easter is celebrated on the same day in years in which the vernal full moon occurs late enough to be after the defined equinoxes of both churches and on a Sunday, Monday, or Tuesday. This is the case for 31 years of the 21st century, but the frequency is decreasing. (It occurred in 47 years in the 17th century, but will happen for the last time in 2698, after which the Easters will be permanently on different dates). It falls one week after Catholic Easter when vernal full moon occurs Wednesday through Saturday, or four or five weeks after Catholic Easter when the Catholic vernal full moon falls before or around 29 March, depending on the day of the week. Among the
Oriental Orthodox, some churches have changed from the Julian to the Gregorian calendar and the date for Easter, as for other fixed and moveable feasts, is the same as in the Western church. The Greek island of
Syros, whose population is divided almost equally between Catholics and Orthodox, is one of the few places where the two Churches share a common date for Easter, with the Catholics accepting the Orthodox date—a practice helping considerably in maintaining good relations between the two communities. Conversely, Orthodox Christians in Finland celebrate Easter according to the
Western Christian date.
Proposed reforms of the date In the 20th and 21st centuries, some individuals and institutions have propounded changing the method of calculating the date for Easter, the most prominent proposal being the Sunday after the second Saturday in April. Despite having some support, proposals to reform the date have not been implemented. An Orthodox congress of Eastern Orthodox bishops, which included representatives mostly from the
Patriarch of Constantinople and the
Serbian Patriarch, met in
Constantinople in 1923, where the bishops agreed to the
Revised Julian calendar. The original form of this calendar would have determined Easter using precise astronomical calculations based on the meridian of
Jerusalem. However, all the Eastern Orthodox countries that subsequently adopted the Revised Julian calendar adopted only that part of the revised calendar that applied to festivals falling on fixed dates in the Julian calendar. The revised Easter computation that had been part of the original 1923 agreement was never permanently implemented in any Orthodox diocese. At a summit in
Aleppo, Syria, in 1997, the
World Council of Churches (WCC) proposed a
reform in the calculation of Easter which would have replaced the present divergent practices of calculating Easter with modern scientific knowledge taking into account actual astronomical instances of the spring equinox and full moon based on the meridian of Jerusalem, while also following the tradition of Easter being on the Sunday following the full moon. The recommended World Council of Churches changes would have sidestepped the calendar issues and eliminated the difference in date between the Eastern and Western churches. The reform was proposed for implementation starting in 2001, and despite repeated calls for reform, it was not ultimately adopted by any member body. In January 2016, the
Anglican Communion,
Coptic Orthodox Church,
Greek Orthodox Church, and Roman Catholic Church again considered agreeing on a common, universal date for Easter, while also simplifying the calculation of that date, with either the second or third Sunday in April being popular choices. In November 2022, the Patriarch of Constantinople said that conversations between the Roman Catholic Church and the Orthodox Churches had begun to determine a common date for the celebration of Easter. The agreement is expected to be reached for the 1700th anniversary of the Council of Nicaea in 2025.
Table of the dates of Easter by Gregorian and Julian calendars The
WCC presented comparative data of the relationships: ==Position in the church year==