Easter Date Calculation – Book of Common Prayer
Easter Sunday (Western Churches) is always the Sunday after the Paschal full moon that occurs on or after the spring equinox (Vernal Equinox) on March 21 (a date which is fixed in accordance with an ancient ecclesiastical computation (which does not always correspond to the astronomical equinox).
- Full Moon 2023: will be shortly after midnight on Thursday morning, April 6, 2023, at 12:35 a.m. EDT.
- Full Moon 2024: April 22nd, the vernal equinox in the Northern Hemisphere occurs on Tuesday, March 19.
- The difference in the dates of Passover and Easter is based on one being a specific calendar day and the other being determined by the solar cycle. For the Jews, Passover always begins on the 15th day of their month of Abib and runs for 8 days. Abib usually falls between April 15-May 15. Although they may observe the Seder meal any day that week, many Jewish families still celebrate on Thursday evening.
- In 2024, which is a leap year, Easter is March 31 and Passover starts April 22.
- In 2025, Easter is April 20 and Passover starts April 12.
- In 2026, Easter is April 5 and Passover starts April 1.
- In 2027, Easter is March 28 and Passover starts April 21.
- In 2028, Easter is April 16 and Passover starts April 10.
The full moon may happen on any date between March 21 and April 18. If the full moon falls on a Sunday, Easter Day is the Sunday following.
- NOTE, That the Full Moon, for the purposes of these Rules and Tables is the Fourteenth Day of a Lunar Month, reckoned according to an ancient Ecclesiastical computation, and not the real or Astronomical Full Moon.”
Easter day cannot be earlier than March 22 or later than April 25th.
- Each LEAP YEAR, the month of February has 29 days instead of 28. Adding one extra day in the calendar every 4 years compensates for the fact that a period of 365 days is shorter than a tropical year by almost 6 hours. (example: 2024, 2028, 2032, ETC.) (pg 882-883 BCP 1979)
Easter – (Western Churches)
Easter is calculated as the first Sunday after the paschal full moon that occurs on or after the vernal equinox. If the full moon falls on a Sunday, then Easter is the following Sunday. The holiday can occur anywhere between March 22 and April 25.
The Western church does not use the actual, or astronomically correct date for the vernal equinox, but a fixed date (March 21). And by full moon it does not mean the astronomical full moon but the “ecclesiastical moon,” which is based on tables created by the church. These constructs allow the date of Easter to be calculated in advance rather than determined by actual astronomical observances, which are naturally less predictable. See also A Tale of Two Easters.
The Council of Nicaea in 325 established that Easter would be celebrated on Sundays; before that Easter was celebrated on different days in different places in the same year. See also dates of other Christian movable feasts.
Easter – (Orthodox Church)
The Orthodox church uses the same formula to calculate Easter but bases the date on a slightly different calendar—the Julian calendar instead of the more contemporary Gregorian one, the calendar that is most widely used today. Consequently, both churches only occasionally celebrate Easter on the same day.
Unlike the Western Church, the Eastern Church sets the date of Easter according to the actual, astronomical full moon and the actual equinox as observed along the meridian of Jerusalem, site of the Crucifixion and Resurrection. See also A Tale of Two Easters and dates of other Orthodox movable feasts.
To calculate Easter Sunday two points of reference must first be determined:
- The Golden Number (The Prime) – Calculated by adding one to the year and dividing the sum by 19. The remainder, if any, is the Golden Number, but if there is no remainder, 19 is the Golden Number. (pg 19-30 BCP 1979)
- There are 19 Golden Numbers,
Far left number in the calendar for late March and early April
- The Sunday Letter (Dominical Letter)- One of the first seven letters of the alphabet, “A” through “g,” is assigned to each date in the calendar year (except Feb. 29) in rotation in the Prayer Book calendar (pp. 19-30). The letter “A” is assigned to Jan. 1, Jan. 8, Jan. 15, etc. The letter “b” is assigned to Jan. 2, Jan. 9, Jan. 16, etc. The Sunday Letter can be used to determine all the dates of the Sundays in a calendar year. For example, if Jan. 1 is a Sunday, “A” is the Sunday Letter.
- Leap Year presents the one exception to this rule. In a Leap Year, the letter corresponding to the date of the first Sunday in Jan. will be the Sunday Letter for the months of Jan. and Feb. However, the Sunday Letter for Mar. through Dec. in a Leap Year will be the letter preceding the Sunday Letter for Jan. and Feb. For example, if “g” is the Sunday Letter in Jan. and Feb. of a Leap Year, “f” will be the Sunday Letter in Mar. through Dec. of that Leap Year. This change results from the additional day (Feb. 29) in a Leap Year.
The following table provides reference to the Sunday Letter of any year between A.D. 1900 and A.D. 2099.
It will be found on the line of the hundredth year above the column that contains the remaining digits of the year.
Leap year, the letter above the number marked with an asterisk is the Sunday Letter for January and February, and the Letter over the number not so marked is the Sunday Letter for the rest of the year.
Example: The Sunday Letter for the year 2023 is A
Calculate Easter Sunday 2023
- The Golden Number prefixed to a day in the month of March or of April in the calendar marks the date of the full moon in that year
- Easter Day will be the next date bearing the Sunday Letter of that year. But when the Golden Number of a given year and the Sunday Letter of that year occur on the same date, then Easter day is one week later. (For example, if the Golden Number is 19—which appears in the Calendar prefixed to March 27––and the Sunday Letter is d, then Easter Day in that year will fall on March 29. If the Golden Number is 10 and the Sunday Letter is A, then Easter Day will fall on April 9. But if the Golden Number is 19 and the Sunday Letter is b, then Easter Day will be one week later, namely April 3.)
2023 CALCULATIONS:
2023 + 1 = 2024
2024 / 19 = 106.526 (106 with a remainder of 10)
Golden Number is 10 – (106 x 19 = 2014, therefore 2024 – 2014 = 10)
Sunday Letter = A
Find the next Sunday with a Sunday Letter (Dominical Letter) of A
Easter Sunday = April 9th for year 2023
2024 Calculations (Leap Year)
2024 + 1 = 2025
2025 / 19 = 106.579 (106 with a remainder of 11)
Golden Number is 11 – (106 x 19 = 2025 – 2014 = 11)
Sunday Letter is “f”
Easter Sunday = March 31st, 2024
Easter, the Christian holiday that celebrates the day of the resurrection of Jesus Christ, is a moveable feast, which means that it does not occur on the same date every year. Easter is calculated based on the phases of the moon and the coming of spring.
Determining the Date of Easter
In 325 A.D., the Council of Nicaea, which agreed upon the basic principles of Christianity, established a formula for the date of Easter as the Sunday following the paschal full moon, which is the full moon that falls on or after the spring equinox. In practice, that means that Easter is always the first Sunday after the first full moon that falls on or after March 21. Easter can occur as early as March 22 and as late as April 25, depending on when the paschal full moon occurs.
You can easily find the date of Easter in this and future years, in both the Western (Gregorian) and Eastern (Julian) calculations online.
The Significance of the Paschal Full Moon
The Council of Nicaea decided that Easter must always occur on a Sunday because Sunday was the day on which Christ rose from the dead. But why is the paschal full moon used to determine the date of Easter? The answer comes from the Jewish calendar. The Aramaic word “paschal” means “pass over,” which is a reference to the Jewish holiday.
Passover fell on the date of the paschal full moon in the Jewish calendar. Jesus Christ was Jewish. His Last Supper with his disciples was a Passover Seder. It is now called Holy Thursday by Christians and is the Thursday immediately before Easter Sunday. Therefore, the very first Easter Sunday was the Sunday after Passover.
Many Christians erroneously believe that the date of Easter is currently determined by the date of Passover, and so they are surprised when Western Christians sometimes celebrated Easter before the Jewish celebration of Passover.
Approximate Dates for the Paschal Moon
The paschal full moon can fall on different days in different time zones, which can present a problem when calculating the date of Easter. If people in different time zones were to calculate the date of Easter depending on when they observed the paschal full moon, then that would mean that the date of Easter would be different depending on which time zone they lived in. For that reason, the church does not use the exact date of the paschal full moon but an approximation.
For calculation purposes, the full moon is always set on the 14th day of the lunar month. The lunar month begins with the new moon. For the same reason, the church sets the date of the spring equinox at March 21, even though the actual vernal equinox can occur on March 20. These two approximations allow the church to set a universal date for Easter, regardless of when you observe the paschal full moon in your time zone.
Occasional Different Date for Eastern Orthodox Christians
Easter is not always celebrated universally by all Christians on the same date. Western Christians, including the Roman Catholic church and Protestant denominations, calculate the date of Easter by using the Gregorian calendar, which is a more astronomically precise calendar that’s used throughout the West today in both the secular and religious worlds.
Eastern Orthodox Christians, such as the Greek and Russian Orthodox Christians, continue to use the older Julian calendar to calculate the date of Easter. The Orthodox Church uses the exact same formula established by the Council of Nicaea for determining the date of Easter only with a different calendar.
Because of the date differences on the Julian calendar, the Eastern Orthodox celebration of Easter always occurs after the Jewish celebration of Passover. Erroneously, Orthodox believers may think their Easter date is tied to Passover, but it isn’t. As the Antiochian Orthodox Christian Archdiocese of North America explained in a 1994 article entitled “The Date of Pascha.”
A Theological Controversy
The Council of Nicaea set up a formula for calculating the date of Easter to separate the Christian celebration of Christ’s Resurrection from the Jewish celebration of Passover.
While Easter and Passover were related historically—the Council of Nicaea ruled that because Christ is symbolically the sacrificial Passover lamb, the holiday of Passover no longer has theological significance for Christians.
From <https://www.learnreligions.com/how-date-of-easter-is-calculated-542413>
How Is Easter Determined?
Easter falls on the first Sunday after the Full Moon date, based on mathematical calculations, that falls on or after March 21. If the Full Moon is on a Sunday, Easter is celebrated on the following Sunday.
Although Easter is liturgically related to the beginning of spring in the Northern Hemisphere (March equinox) and the Full Moon, its date is not based on the actual astronomical date of either event.
- March 21 is the Church’s date of the March equinox, regardless of the time zone, while the actual date of the equinox varies between March 19 and March 22, and the date depends on the time zone.
- The date of the Paschal Full Moon, used to determine the date of Easter, is based on mathematical approximations following a 19-year cycle called the Metonic cycle.
Both dates may coincide with the dates of the astronomical events, but in some years, they don’t.
Astronomical vs. Ecclesiastical Dates
In years in which the Church’s March equinox and Paschal Full Moon dates do not coincide with the astronomical dates of these events, there may be some confusion about the date of Easter. In 2019, for example, the March equinox in the Western Hemisphere happened on Wednesday, March 20, while the first Full Moon in spring was on Thursday, March 21 in many time zones. If the Church followed the timing of these astronomical events, Easter would have been celebrated on March 24, the Sunday after the Full Moon on March 21.
However, the Full Moon date in March specified by the Church’s lunar calendar, also called the ecclesiastical Full Moon, was March 20, 2019—one day before the ecclesiastical date of the March equinox, March 21. For that reason, the Easter date 2019 was based on the next ecclesiastical Full Moon, on April 18. This is why Easter Sunday 2019 was on April 21.
Earliest and Latest Easter Dates
According to the Metonic cycle, the Paschal Full Moon falls on a recurring sequence of 19 dates ranging from March 21 to April 18. Since Easter happens on the Sunday following the Paschal Full Moon, it can fall on any date between March 22 and April 25. (Note: this applies only to years 1753-2400).
List of years with earliest and latest Easter dates
Holidays Related to Easter
The dates of many Christian feasts are based on the date of Easter Sunday. For example:
- Mardi Gras / Carnival Tuesday (47 days before Easter)
- Ash Wednesday (46 days before Easter)
- Palm Sunday (1 week before Easter)
- Maundy Thursday (3 days before Easter)
- Good Friday (2 days before Easter)
- Holy Saturday (1 day before Easter)
- Easter Monday (1 day after Easter)
- Ascension Day (39 days after Easter)
- Whit Sunday / Pentecost (49 days after Easter)
- Whit Monday (50 days after Easter)
- Trinity Sunday (56 days after Easter)
- Corpus Christi (60 days after Easter)
Why Is Easter Celebrated in Spring?
According to the Bible, Jesus Christ’s death and resurrection occurred at the time of the Jewish Passover, which was celebrated on the first Full Moon following the vernal equinox. This soon led to Christians celebrating Easter on different dates. At the end of the 2nd century, some congregations celebrated Easter on the day of the Passover, while others celebrated it on the following Sunday.
In 325 CE, the Council of Nicaea established that Easter would be held on the first Sunday after the first Full Moon occurring on or after the vernal equinox. (*) From that point forward, the Easter date depended on the ecclesiastical approximation of March 21 for the vernal equinox.
Orthodox Easter
Not all Christians observe Easter according to the Gregorian calendar; most Orthodox Christians still follow the Julian calendar.
Like the Easter date based on the Gregorian calendar, Orthodox Easter falls on a Sunday between March 22 and April 25 in the Julian calendar (years 1753-2400). In the Gregorian calendar, this corresponds to April 3 to May 10.
In some years, Orthodox Easter falls on the same day as western Easter. The next time the two Easter dates coincide will be in 2025 (April 20).
Proposed Easter Date Reforms
There have been a number of suggested reforms for the Easter date. For example, in 1997, the World Council of Churches proposed a reform of the Easter calculation to replace an equation-based method of calculating Easter with direct astronomical observation.
This would have solved the Easter date difference between churches that observe the Gregorian calendar and those that observe the Julian calendar. The reform was proposed to be implemented in 2001, but it is not yet adopted.
Another example of a proposed reform occurred in the United Kingdom, where the Easter Act 1928 was established to allow the Easter date to be fixed as the first Sunday after the second Saturday in April. However, this law was not implemented, although it remains on the UK Statute Law Database.
Earliest Easter Dates in Years 1753-2400
| Gregorian Calendar | Julian Calendar | ||
| Day | Year | Day | Year |
| March 22 | 1761 | April 3 | 1763 |
| March 22 | 1818 | April 4 | 1790 |
| March 22 | 2285 | April 4 | 1847 |
| March 22 | 2353 | April 4 | 1858 |
| March 23 | 1788 | April 4 | 1915 |
| March 23 | 1845 | April 4 | 2010 |
| March 23 | 1856 | April 5 | 1801 |
| March 23 | 1913 | April 5 | 1885 |
| March 23 | 2008 | April 5 | 1896 |
| March 23 | 2160 | April 5 | 1942 |
| March 23 | 2228 | April 5 | 1953 |
| March 23 | 2380 | April 5 | 2037 |
| April 5 | 2048 | ||
| April 5 | 2105 | ||
| Note: All Julian dates are converted to Gregorian calendar dates |
Latest Easter Dates in Years 1753-2400
| Gregorian Calendar | Julian Calendar | ||
| Day | Year | Day | Year |
| April 23 | 1848 | May 7 | 2051 |
| April 23 | 1905 | May 7 | 2271 |
| April 23 | 1916 | May 7 | 2344 |
| April 23 | 2000 | May 8 | 1983 |
| April 23 | 2079 | May 8 | 2078 |
| April 23 | 2152 | May 8 | 2135 |
| April 23 | 2220 | May 8 | 2146 |
| April 24 | 1791 | May 8 | 2203 |
| April 24 | 1859 | May 8 | 2287 |
| April 24 | 2011 | May 8 | 2298 |
| April 24 | 2095 | May 8 | 2355 |
| April 24 | 2163 | May 8 | 2366 |
| April 24 | 2231 | May 9 | 2173 |
| April 24 | 2383 | May 9 | 2230 |
| April 25 | 1886 | May 9 | 2241 |
| April 25 | 1943 | May 9 | 2382 |
| April 25 | 2038 | May 9 | 2393 |
| May 10 | 2268 | ||
| May 10 | 2325 | ||
| May 10 | 2336 | ||
| All Julian dates are converted to Gregorian calendar dates |
(*) The resolution’s exact wording is unknown, so the council’s precise contribution to the process of determining the date of Easter is disputed. However, according to some historians, contemporary sources (e.g., by Epiphanius of Salamis and Socrates of Constantinople) suggest that the council decided on an Easter date after the spring equinox.
From <https://www.timeanddate.com/calendar/determining-easter-date.html>
