Astronomical Society of South Australia - ASSA

 

Raising community participation and awareness in astronomy

 

Calculate the Date of Easter Sunday

This Document Explains:

  • The complete procedure for calculating Easter Sunday dates for all years 326 to 4099 A.D.
  • How to work out Easter Sunday dates quickly and easily for yourself.
  • The Easter Method Calculation.
  • The way in which Easter dating methods evolved, and provides
  • Lists of Easter Sunday dates for the last 300 and next 300 years.

List of Easter Sunday Dates

This year Easter Sunday is on 5th April 2015

Easter Dating Method

This simplified Easter Dating Method was produced by Ronald W. Mallen
Research by Ronald W. Mallen, Adelaide, Australia
Programming algorithm by Greg Mallen

 

List of Easter Sunday Dates 1700-1799
   11th April 1700    1st April 1725   29th March 1750   16th April 1775
   27th March 1701   21st April 1726   11th April 1751    7th April 1776
   16th April 1702   13th April 1727    2nd April 1752   30th March 1777
    8th April 1703   28th March 1728   22nd April 1753   19th April 1778
   23rd March 1704   17th April 1729   14th April 1754    4th April 1779
   12th April 1705    9th April 1730   30th March 1755   26th March 1780
    4th April 1706   25th March 1731   18th April 1756   15th April 1781
   24th April 1707   13th April 1732   10th April 1757   31st March 1782
    8th April 1708    5th April 1733   26th March 1758   20th April 1783
   31st March 1709   25th April 1734   15th April 1759   11th April 1784
   20th April 1710   10th April 1735    6th April 1760   27th March 1785
    5th April 1711    1st April 1736   22nd March 1761   16th April 1786
   27th March 1712   21st April 1737   11th April 1762    8th April 1787
   16th April 1713    6th April 1738    3rd April 1763   23rd March 1788
    1st April 1714   29th March 1739   22nd April 1764   12th April 1789
   21st April 1715   17th April 1740    7th April 1765    4th April 1790
   12th April 1716    2nd April 1741   30th March 1766   24th April 1791
   28th March 1717   25th March 1742   19th April 1767    8th April 1792
   17th April 1718   14th April 1743    3rd April 1768   31st March 1793
    9th April 1719    5th April 1744   26th March 1769   20th April 1794
   31st March 1720   18th April 1745   15th April 1770    5th April 1795
   13th April 1721   10th April 1746   31st March 1771   27th March 1796
    5th April 1722    2nd April 1747   19th April 1772   16th April 1797
   28th March 1723   14th April 1748   11th April 1773    8th April 1798
   16th April 1724    6th April 1749    3rd April 1774   24th March 1799

INDEX

List of Easter Sunday Dates 1800-1899
   13th April 1800    3rd April 1825   31st March 1850   28th March 1875
    5th April 1801   26th March 1826   20th April 1851   16th April 1876
   18th April 1802   15th April 1827   11th April 1852    1st April 1877
   10th April 1803    6th April 1828   27th March 1853   21st April 1878
    1st April 1804   19th April 1829   16th April 1854   13th April 1879
   14th April 1805   11th April 1830    8th April 1855   28th March 1880
    6th April 1806    3rd April 1831   23rd March 1856   17th April 1881
   29th March 1807   22nd April 1832   12th April 1857    9th April 1882
   17th April 1808    7th April 1833    4th April 1858   25th March 1883
    2nd April 1809   30th March 1834   24th April 1859   13th April 1884
   22nd April 1810   19th April 1835    8th April 1860    5th April 1885
   14th April 1811    3rd April 1836   31st March 1861   25th April 1886
   29th March 1812   26th March 1837   20th April 1862   10th April 1887
   18th April 1813   15th April 1838    5th April 1863    1st April 1888
   10th April 1814   31st March 1839   27th March 1864   21st April 1889
   26th March 1815   19th April 1840   16th April 1865    6th April 1890
   14th April 1816   11th April 1841    1st April 1866   29th March 1891
    6th April 1817   27th March 1842   21st April 1867   17th April 1892
   22nd March 1818   16th April 1843   12th April 1868    2nd April 1893
   11th April 1819    7th April 1844   28th March 1869   25th March 1894
    2nd April 1820   23rd March 1845   17th April 1870   14th April 1895
   22nd April 1821   12th April 1846    9th April 1871    5th April 1896
    7th April 1822    4th April 1847   31st March 1872   18th April 1897
   30th March 1823   23rd April 1848   13th April 1873   10th April 1898
   18th April 1824    8th April 1849    5th April 1874    2nd April 1899

INDEX

List of Easter Sunday Dates 1900-1999
   15th April 1900   12th April 1925    9th April 1950   30th March 1975
    7th April 1901    4th April 1926   25th March 1951   18th April 1976
   30th March 1902   17th April 1927   13th April 1952   10th April 1977
   12th April 1903    8th April 1928    5th April 1953   26th March 1978
    3rd April 1904   31st March 1929   18th April 1954   15th April 1979
   23rd April 1905   20th April 1930   10th April 1955    6th April 1980
   15th April 1906    5th April 1931    1st April 1956   19th April 1981
   31st March 1907   27th March 1932   21st April 1957   11th April 1982
   19th April 1908   16th April 1933    6th April 1958    3rd April 1983
   11th April 1909    1st April 1934   29th March 1959   22nd April 1984
   27th March 1910   21st April 1935   17th April 1960    7th April 1985
   16th April 1911   12th April 1936    2nd April 1961   30th March 1986
    7th April 1912   28th March 1937   22nd April 1962   19th April 1987
   23rd March 1913   17th April 1938   14th April 1963    3rd April 1988
   12th April 1914    9th April 1939   29th March 1964   26th March 1989
    4th April 1915   24th March 1940   18th April 1965   15th April 1990
   23rd April 1916   13th April 1941   10th April 1966   31st March 1991
    8th April 1917    5th April 1942   26th March 1967   19th April 1992
   31st March 1918   25th April 1943   14th April 1968   11th April 1993
   20th April 1919    9th April 1944    6th April 1969    3rd April 1994
    4th April 1920    1st April 1945   29th March 1970   16th April 1995
   27th March 1921   21st April 1946   11th April 1971    7th April 1996
   16th April 1922    6th April 1947    2nd April 1972   30th March 1997
    1st April 1923   28th March 1948   22nd April 1973   12th April 1998
   20th April 1924   17th April 1949   14th April 1974    4th April 1999

INDEX

List of Easter Sunday Dates 2000-2099
   23rd April 2000   20th April 2025   10th April 2050    7th April 2075
   15th April 2001    5th April 2026    2nd April 2051   19th April 2076
   31st March 2002   28th March 2027   21st April 2052   11th April 2077
   20th April 2003   16th April 2028    6th April 2053    3rd April 2078
   11th April 2004    1st April 2029   29th March 2054   23rd April 2079
   27th March 2005   21st April 2030   18th April 2055    7th April 2080
   16th April 2006   13th April 2031    2nd April 2056   30th March 2081
    8th April 2007   28th March 2032   22nd April 2057   19th April 2082
   23rd March 2008   17th April 2033   14th April 2058    4th April 2083
   12th April 2009    9th April 2034   30th March 2059   26th March 2084
    4th April 2010   25th March 2035   18th April 2060   15th April 2085
   24th April 2011   13th April 2036   10th April 2061   31st March 2086
    8th April 2012    5th April 2037   26th March 2062   20th April 2087
   31st March 2013   25th April 2038   15th April 2063   11th April 2088
   20th April 2014   10th April 2039    6th April 2064    3rd April 2089
    5th April 2015    1st April 2040   29th March 2065   16th April 2090
   27th March 2016   21st April 2041   11th April 2066    8th April 2091
   16th April 2017    6th April 2042    3rd April 2067   30th March 2092
    1st April 2018   29th March 2043   22nd April 2068   12th April 2093
   21st April 2019   17th April 2044   14th April 2069    4th April 2094
   12th April 2020    9th April 2045   30th March 2070   24th April 2095
    4th April 2021   25th March 2046   19th April 2071   15th April 2096
   17th April 2022   14th April 2047   10th April 2072   31st March 2097
    9th April 2023    5th April 2048   26th March 2073   20th April 2098
   31st March 2024   18th April 2049   15th April 2074   12th April 2099

INDEX

List of Easter Sunday Dates 2100-2199
   28th March 2100   22nd April 2125   12th April 2150    9th April 2175
   17th April 2101   14th April 2126    4th April 2151   31st March 2176
    9th April 2102   30th March 2127   23rd April 2152   20th April 2177
   25th March 2103   18th April 2128   15th April 2153    5th April 2178
   13th April 2104   10th April 2129   31st March 2154   28th March 2179
    5th April 2105   26th March 2130   20th April 2155   16th April 2180
   18th April 2106   15th April 2131   11th April 2156    1st April 2181
   10th April 2107    6th April 2132   27th March 2157   21st April 2182
    1st April 2108   19th April 2133   16th April 2158   13th April 2183
   21st April 2109   11th April 2134    8th April 2159   28th March 2184
    6th April 2110    3rd April 2135   23rd March 2160   17th April 2185
   29th March 2111   22nd April 2136   12th April 2161    9th April 2186
   17th April 2112    7th April 2137    4th April 2162   25th March 2187
    2nd April 2113   30th March 2138   24th April 2163   13th April 2188
   22nd April 2114   19th April 2139    8th April 2164    5th April 2189
   14th April 2115    3rd April 2140   31st March 2165   25th April 2190
   29th March 2116   26th March 2141   20th April 2166   10th April 2191
   18th April 2117   15th April 2142    5th April 2167    1st April 2192
   10th April 2118   31st March 2143   27th March 2168   21st April 2193
   26th March 2119   19th April 2144   16th April 2169    6th April 2194
   14th April 2120   11th April 2145    1st April 2170   29th March 2195
    6th April 2121    3rd April 2146   21st April 2171   17th April 2196
   29th March 2122   16th April 2147   12th April 2172    9th April 2197
   11th April 2123    7th April 2148    4th April 2173   25th March 2198
    2nd April 2124   30th March 2149   17th April 2174   14th April 2199

INDEX

List of Easter Sunday Dates 2200-2299
    6th April 2200   27th March 2225   21st April 2250   18th April 2275
   19th April 2201   16th April 2226   13th April 2251    2nd April 2276
   11th April 2202    8th April 2227   28th March 2252   22nd April 2277
    3rd April 2203   23rd March 2228   17th April 2253   14th April 2278
   22nd April 2204   12th April 2229    9th April 2254   30th March 2279
    7th April 2205    4th April 2230   25th March 2255   18th April 2280
   30th March 2206   24th April 2231   13th April 2256   10th April 2281
   19th April 2207    8th April 2232    5th April 2257   26th March 2282
    3rd April 2208   31st March 2233   25th April 2258   15th April 2283
   26th March 2209   20th April 2234   10th April 2259    6th April 2284
   15th April 2210    5th April 2235    1st April 2260   22nd March 2285
   31st March 2211   27th March 2236   21st April 2261   11th April 2286
   19th April 2212   16th April 2237    6th April 2262    3rd April 2287
   11th April 2213    1st April 2238   29th March 2263   22nd April 2288
   27th March 2214   21st April 2239   17th April 2264    7th April 2289
   16th April 2215   12th April 2240    2nd April 2265   30th March 2290
    7th April 2216    4th April 2241   25th March 2266   19th April 2291
   30th March 2217   17th April 2242   14th April 2267   10th April 2292
   12th April 2218    9th April 2243    5th April 2268   26th March 2293
    4th April 2219   31st March 2244   18th April 2269   15th April 2294
   23rd April 2220   13th April 2245   10th April 2270    7th April 2295
   15th April 2221    5th April 2246    2nd April 2271   19th April 2296
   31st March 2222   28th March 2247   21st April 2272   11th April 2297
   20th April 2223   16th April 2248    6th April 2273    3rd April 2298
   11th April 2224    1st April 2249   29th March 2274   16th April 2299

INDEX

How is Easter Sunday Date Determined?

SUMMARY

Easter Sunday is the Sunday following the Paschal Full Moon (PFM) date for the year.   (Paschal is pronounced "PAS-KUL", not "pas-chal").   See Christian Prayer Books for proof of this concise definition.

In June 325 A.D. astronomers approximated astronomical full moon dates for the Christian church, calling them Ecclesiastical Full Moon (EFM) dates.   From 326 A.D. the PFM date has always been the EFM date after March 20 (which was the equinox date in 325 A.D.)

From 1583, each PFM date differs from an Astronomical Full Moon (AFM) date usually by no more than 1 date, and never by more than 3 dates.   (Each AFM is a two-dates event due to world time zones.   Each PFM is a one-date event world-wide).

HISTORY

Easter Sunday is the date of the annual celebration of Christ's resurrection.   The aim of the Easter Dating Method is to maintain, for each Easter Sunday, the same season of the year and the same relationship to the preceding astronomical full moon that occurred at the time of his resurrection in 30 A.D.

This was achieved in 1583 A.D. using skill and common-sense by Pope Gregory the 13th, and his astronomers and mathematicians, predominantly Lilius and Clavius, by introducing their new larger (revised) PFM Gregorian dates table.   This replaced the (original) 326 A.D. "19 PFM dates" table in the Julian calendar.

Easter Sunday, from 326 A.D., is always one of the 35 dates March 22 to April 25.

From 31 A.D. to 325 A.D. Easter Day was celebrated either:
(a) on or just after the first day of the Jewish Passover (no matter on which day of the week that Easter Day occurred), or
(b) on a Sunday close to or on the first Passover Day.
Both of these methods existed continuously throughout this period.

From 326 A.D. to 1582 A.D. Easter Sunday date was based on the Julian calendar in use at that time.   It became defined as the Sunday following the Paschal Full Moon date for the year, using a simple "19 PFM dates" table.   Precise information on this subject can be found on pages 415 to 425 of the Explanatory Supplement to the 1961 Astronomical Ephemeris.

The Julian calendar was replaced by the Gregorian calendar in October 1582 to re-align March 20 (and therefore Easter) with the seasons by removing 10 dates October 5 to 14, 1582.   This replacement did not occur until later in many countries e.g. in September 1752 in England.   See GM Arts Easter Date Calculations for more information.   ENGLISH Easter Sunday dates for 1583 to 1752 can be calculated using information near the end of this Easter Dating Method document.

The Gregorian calendar very closely maintains the alignment of seasons and calendar dates by having leap years in only 1 of every 4 century years, namely, those divisible exactly by 400.   One additional February 29 date will need to be removed in about 4140 A.D., therefore Easter calculations will need to use the changed Days of Week of PFM dates when the exact year for this removal is decided.

From 326 A.D., the Easter Sunday Date for any given year is NOT determined by the March Equinox date for that year.   March 20 (not March 21) is the most common Gregorian Equinox date from 1583 to 4099 A.D.

Historically, references to March 21 have caused mistakes in calculating Easter Sunday dates.   March 20 has become the important date in recent Easter dating methods.   Despite frequent references to March 21, this date has no special significance to any recent Easter dating methods.  

The present method describing the Easter Dating Procedure can be found in Christian Prayer Books.   This procedure has been dramatically simplified by Ronald W. Mallen, Adelaide, South Australia.   See Finding Easter Sunday Dates with a Calculator for a clear and unique explanation of this procedure.

ORTHODOX CHURCHES

Orthodox churches became fully autonomous in 1054 A.D., and celebrate their Easter always on the basis of the Julian calendar and the "19 PFM dates" table.   The Julian calendar date Thursday October 4, 1582 was followed by the Gregorian calendar date Friday October 15, 1582.   The 10 dates October 5 to 14 were removed.

Consequently, their Easter Sunday dates are identical up to 1582, then from 1583 onwards often differ from those of Western churches.

In some years the Orthodox Easter Sunday occurs on the same day as the Western Easter Sunday.   For example, this occurred in 1990 because the Western Easter Sunday date of (Gregorian calendar) April 15, 1990 is the same as the Orthodox Easter Sunday date of (Julian calendar) April 2, 1990.   In most years, Orthodox Easter follows Western Easter by one or more weeks.

To determine the Orthodox Easter Sunday date, it is first necessary to find the Julian Easter Sunday date, then to add the number of days which have been "skipped" in the Gregorian calendar.   See Finding Orthodox Easter Sunday Dates with a Calculator for a simple explanation of this procedure.

INDEX

Finding Easter Sunday Dates with a Calculator

This procedure is a dramatic and accurate simplification of the official procedure used to calculate Easter Sunday dates, as described in Christian Prayer Books.   Paschal Full Moon dates are copied directly from these Books.   It was produced in 1995 by Ronald W. Mallen, Adelaide, South Australia.   It requires just one division on a calculator, and three simple additions.

This procedure appears more compactly in the 1988 Australian Almanac (titled "The Dating of Easter") held in the Canberra Library, Australia.

There are three steps to calculating the Easter Sunday date:
Step 1) Obtain the Paschal Full Moon (PFM) date from Table A
Step 2) Add the 3 numbers obtained from Tables B, C and D
Step 3) Find the Easter Sunday date from Table E

STEP 1

Table A below shows PFM dates for years 326 to 2599 A.D. If you're looking further into the future, click here to see another Table A for years 2600 to 4099 A.D.

  • Use a calculator to divide the year by 19
  • Obtain the 3 digits after the decimal point
  • Find the Paschal Full Moon (PFM) date in Table A below
  • Then continue below with Step 2

Year 2285 example: 2285 ÷ 19 = 120.263157, so use the .263 part to find the PFM date in Table A.   The result is March 21, 2285 A.D.

Table A: PFM Date for Years 326 to 2599 (M=March, A=April)
Fraction
after dividing
year by 19
326
- 1582
1583
- 1699
1700
- 1899
1900
- 2199
2200
- 2299
2300
- 2399
2400
- 2499
2500
- 2599
.0 (none) A5 A12 A13 A14 A15 A16
.052 M25 A1 A2 A3 A4 A5
.105 A13 M21 M22 M23 M24 M25
.157 A2 A9 A10 A11 A12 A13
.210 M22 M29 M30 M31 A1 A2
.263 A10 A17 A18 A18 M21 M22
.315 M30 A6 A7 A8 A9 A10
.368 A18 M26 M27 M28 M29 M30
.421 A7 A14 A15 A16 A17 A18
.473 M27 A3 A4 A5 A6 A7
.526 A15 M23 M24 M25 M26 M27
.578 A4 A11 A12 A13 A14 A15
.631 M24 M31 A1 A2 A3 A4
.684 A12 A18 M21 M22 M23 M24
.736 A1 A8 A9 A10 A11 A12
.789 M21 M28 M29 M30 M31 A1
.842 A9 A16 A17 A17 A18 M21
.894 M29 A5 A6 A7 A8 A9
.947 A17 M25 M26 M27 M28 M29

STEP 2

Add the 3 numbers you obtain from the "result" lines of Tables B, C and D below.

For example, the year 2285 gives us a PFM date of M21 in Table A (for years 326 to 2599 A.D.)

  • M21 gives 2 from Table B
  • the 22 in 2285 gives 3 from Table C
  • the 85 in 2285 gives 1 from Table D

The total of these results is: 2 + 3 + 1 = 6

Table B: PFM Date for year
(M=March, A=April)
  - - M21 M22 M23 M24 M25
  M26 M27 M28 M29 M30 M31 A1
  A2 A3 A4 A5 A6 A7 A8
  A9 A10 A11 A12 A13 A14 A15
  A16 A17 A18 - - - -
Result:0123456

 

Table C: First 2 digits of year
(eg 19 for 1995, or 03 for 326)
  - - - - 03 04 05
  06 07 08 09 10 11 12
  13 14 15* - - 15* 16
  - 17 - 18 - 19 20
  - 21 - 22 - 23 24
  - 25 - 26 - 27 28
  - 29 - 30 - 31 32
  - 33 - 34 - 35 36
  - 37 - 38 - 39 40
Result:6543210

* for years 1500 to 1582, use the result of 4
*
for years 1583 to 1599, use the result of 1

Table D: Last 2 digits of year
  00 01 02 03 - 04 05
  06 07 - 08 09 10 11
  - 12 13 14 15 - 16
  17 18 19 - 20 21 22
  23 - 24 25 26 27 -
  28 29 30 31 - 32 33
  34 35 - 36 37 38 39
  - 40 41 42 43 - 44
  45 46 47 - 48 49 50
  51 - 52 53 54 55 -
  56 57 58 59 - 60 61
  62 63 - 64 65 66 67
  - 68 69 70 71 - 72
  73 74 75 - 76 77 78
  79 - 80 81 82 83 -
  84 85 86 87 - 88 89
  90 91 - 92 93 94 95
  - 96 97 98 99 - -
Result:0123456

STEP 3

Use the total result from step 2 to find the day of week of the PFM date in Table E, then add the number of days shown to the PFM date to find the Easter Sunday date.

For example, year 2285 gave us a PFM date of March 21, and step 2 gave us a total result of 6.   Looking at Table E, this 6 shows that this PFM date occurs on a Saturday, so we need to add 1 day to find the next Sunday, which is March 22, the Easter Sunday date for the year 2285 A.D.

Table E: Following Sunday
Step 2 result: 0 1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 - -
Day of week
of PFM date:
Sun Mon Tue Wed Thu Fri Sat
Days to add for
next Sunday:
7654321

Other examples:
Julian calendar example:
Year 887: Step 1: PFM=A12, Step 2: 3+4+3 = 10, Step 3: A12+4 = April 16, 887
Gregorian calendar examples:
Year 1987: Step 1: PFM=A13, Step 2: 4+1+3 = 8, Step 3: A13+6 = April 19, 1987
Year 2987: Step 1: PFM=A4, Step 2: 2+5+3=10, Step 3: A4+4 = April 8, 2987
Year 3987: Step 1: PFM=M27, Step 2: 1+1+3=5, Step 3: M27+2 = March 29, 3987

INDEX


Table A - PFM Dates for Years 2600 - 4099

  • Use a calculator to divide the year by 19
  • Obtain the 3 digits after the decimal point
  • Find the Paschal Full Moon (PFM) date in Table A below
  • Then click here to continue your calculation
Table A: PFM Date for Years 2600 - 4099 (M=March, A=April)
Fraction
after dividing
year by 19
2600
- 2899
2900
- 3099
3100
- 3399
3400
- 3499
3500
- 3599
3800
- 4099
3600
- 3699
3700
- 3799
.0 (none) A17 A18 A18 M21 M22 M23
.052 A6 A7 A8 A9 A10 A11
.105 M26 M27 M28 M29 M30 M31
.157 A14 A15 A16 A17 A18 A18
.210 A3 A4 A5 A6 A7 A8
.263 M23 M24 M25 M26 M27 M28
.315 A11 A12 A13 A14 A15 A16
.368 M31 A1 A2 A3 A4 A5
.421 A18 M21 M22 M23 M24 M25
.473 A8 A9 A10 A11 A12 A13
.526 M28 M29 M30 M31 A1 A2
.578 A16 A17 A17 A18 M21 M22
.631 A5 A6 A7 A8 A9 A10
.684 M25 M26 M27 M28 M29 M30
.736 A13 A14 A15 A16 A17 A17
.789 A2 A3 A4 A5 A6 A7
.842 M22 M23 M24 M25 M26 M27
.894 A10 A11 A12 A13 A14 A15
.947 M30 M31 A1 A2 A3 A4

INDEX


Finding Orthodox Easter Sunday Dates with a Calculator

This accurate procedure applies to Orthodox churches, which always base their calculations on the Julian calendar and the "19 PFM dates" table.   It applies from the year 1054 A.D., and takes no account whatsoever of the changes resulting from the introduction of the Gregorian calendar in 1582.   This is the current situation in 2002.

These instructions show the procedure for years 1054 to 3399 A.D.   However, this simple method continues indefinitely, because the Julian calendar always has a February 29 date in every fourth year.

There are four steps to calculating the Orthodox Easter Sunday date:

Step 1) Obtain the Paschal Full Moon (PFM) date from Table A
Step 2) Add the 3 numbers obtained from Tables B, C and D
Step 3) Find the Julian Orthodox Easter Sunday date from Table E
Step 4) Convert this Julian date to the Gregorian calendar date from Table F

STEP 1

Table A below shows PFM dates from 1054 AD.  

  • Use a calculator to divide the year by 19
  • Obtain the 3 digits after the decimal point
  • Find the Paschal Full Moon (PFM) date in Table A below
  • Then continue below with Step 2

Year 1995 example: 1995 ÷ 19 = 105 exactly, so use the digits after the decimal point (none in this case) to find the PFM date in Table A.   The result is April 5, 1995.

Table A:
19 PFM Dates

(M=March, A=April)
Fraction
after dividing
year by 19
PFM Date
.0 (none) A5
.052 M25
.105 A13
.157 A2
.210 M22
.263 A10
.315 M30
.368 A18
.421 A7
.473 M27
.526 A15
.578 A4
.631 M24
.684 A12
.736 A1
.789 M21
.842 A9
.894 M29
.947 A17

STEP 2

Add the 3 numbers you obtain from the "result" lines of Tables B, C and D below.

For example, the year 1995 gave us a PFM date of A5 in Table A

  • A5 gives 3 from Table B
  • the 19 in 1995 gives 0 from Table C
  • the 95 in 1995 gives 6 from Table D

The total of these results is: 3 + 0 + 6 = 9

Table B: PFM Date for year
(M=March, A=April)
  - - M21 M22 M23 M24 M25
  M26 M27 M28 M29 M30 M31 A1
  A2 A3 A4 A5 A6 A7 A8
  A9 A10 A11 A12 A13 A14 A15
  A16 A17 A18 - - - -
Result:0123456

 

Table C: First 2 digits of year
(eg 19 for 1995)
  - - - - 10 11 12
  13 14 15 16 17 18 19
  20 21 22 23 24 25 26
  27 28 29 30 31 32 33
Result:6543210

 

Table D: Last 2 digits of year
  00 01 02 03 - 04 05
  06 07 - 08 09 10 11
  - 12 13 14 15 - 16
  17 18 19 - 20 21 22
  23 - 24 25 26 27 -
  28 29 30 31 - 32 33
  34 35 - 36 37 38 39
  - 40 41 42 43 - 44
  45 46 47 - 48 49 50
  51 - 52 53 54 55 -
  56 57 58 59 - 60 61
  62 63 - 64 65 66 67
  - 68 69 70 71 - 72
  73 74 75 - 76 77 78
  79 - 80 81 82 83 -
  84 85 86 87 - 88 89
  90 91 - 92 93 94 95
  - 96 97 98 99 - -
Result:0123456

STEP 3

Use the total result from step 2 to find the day of week of the PFM date in Table E, then add the number of days shown to the PFM date to find the Julian calendar Easter Sunday date.

For example, year 1995 gave us a PFM date of April 5, and step 2 gave us a total result of 9.   Looking at Table E, this 9 shows that this PFM date occurs on a Tuesday, so we need to add 5 days to find the next Sunday, which is April 10.   This date is the Julian calendar Orthodox Easter Sunday date for year 1995.

If the year itself is also Julian (e.g. for Greece in years 1054 to 1922) then this Julian date (e.g. April 3 in 1922) is their Orthodox Easter Sunday date for that year.

ENGLAND used the Julian calendar until 1752, so its Easter Sunday dates are obtained by using steps 1, 2 and 3 (but not 4) of the Orthodox Method stated here.   For example, English Easter Sunday date for 1750 A.D. = A13 + 2 = April 15 in the Julian calendar.   From 1753 England adopted the (revised) PFM Gregorian dates Table A and subsequent tables used in the calculations above.

Table E: Following Sunday
Step 2 result: 0 1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 - -
Day of week
of PFM date:
Sun Mon Tue Wed Thu Fri Sat
Days to add for
next Sunday:
7654321

STEP 4

The Gregorian calendar omits certain February 29 dates to keep its dates aligned with the seasons and position of Earth in relation to the Sun.   To convert the Julian date to the Gregorian date, it is necessary to add the number of days shown in Table F.

Step 4 must be ignored if the Easter Sunday date calculated after step 3 occurred when the Julian calendar was still in use.

The example for year 1995 gives the Julian Easter Sunday date of April 10, and Table F shows that we need to add 13 days to convert it to the Gregorian calendar date of April 23.   This date is the Gregorian calendar Orthodox Easter Sunday date for year 1995 A.D.

Table F:
Convert to Gregorian Calendar
YearDays to Add
1583 to 1699 10
1700 to 1799 11
1800 to 1899 12
1900 to 2099 13
2100 to 2199 14
2200 to 2299 15
2300 to 2499 16
2500 to 2599 17
2600 to 2699 18
2700 to 2899 19
2900 to 2999 20
3000 to 3099 21
3100 to 3299 22
3300 to 3399 23

Other examples:

Year 1994: Step 1: PFM=A17, Step 2: 1+0+5 = 6, Step 3: A17+1=Julian April 18, 1994, Step 4: Julian A18 + 13 = Gregorian May 1, 1994

Year 2870: Step 1: PFM=M25, Step 2: 6+5+3 = 14, Step 3: M25+7=Julian April 1, 2870, Step 4: Julian A1 + 19 = Gregorian April 20, 2870

INDEX


Easter Algorithm for a Computer Program

Here is an algorithm written in BASIC to calculate the Gregorian Easter Sunday date for years 1583 to 4099 (Western churches only).   BASIC code is fairly straightforward, and can easily be converted to other programming languages.

Some typical questions about Easter are:
Q1) "When was Easter Sunday last on April 10?"
Q2) "When does Good Friday next occur on March 30?"
Q3) "How many times has Easter Sunday occurred on April 25 since 1583?"
Answers to these questions can be determined by placing this code within DO...WHILE or FOR...NEXT loops to search or count.

Sub EasterDate (d, m, y)

' EASTER DATE CALCULATION FOR YEARS 1583 TO 4099

' y is a 4 digit year 1583 to 4099
' d returns the day of the month of Easter
' m returns the month of Easter

' Easter Sunday is the Sunday following the Paschal Full Moon
' (PFM) date for the year

' This algorithm is an arithmetic interpretation of the 3 step
' Easter Dating Method developed by Ron Mallen 1985, as a vast
' improvement on the method described in the Common Prayer Book

' Because this algorithm is a direct translation of the
' official tables, it can be easily proved to be 100% correct

' This algorithm derives values by sequential inter-dependent
' calculations, so ... DO NOT MODIFY THE ORDER OF CALCULATIONS!

' The \ operator may be unfamiliar - it means integer division
' for example, 30 \ 7 = 4 (the remainder is ignored)

' All variables are integer data types

' It's free!  Please do not modify code or comments!
' ==========================================================
   Dim FirstDig, Remain19, temp    'intermediate results
   Dim tA, tB, tC, tD, tE          'table A to E results

   FirstDig = y \ 100              'first 2 digits of year
   Remain19 = y Mod 19             'remainder of year / 19

' calculate PFM date
   temp = (FirstDig - 15) \ 2 + 202 - 11 * Remain19
    
   Select Case FirstDig
      Case 21, 24, 25, 27 To 32, 34, 35, 38
         temp = temp - 1
      Case 33, 36, 37, 39, 40
         temp = temp - 2
   End Select
   temp = temp Mod 30

   tA = temp + 21
   If temp = 29 Then tA = tA - 1
   If (temp = 28 And Remain19 > 10) Then tA = tA - 1

'find the next Sunday
   tB = (tA - 19) Mod 7
    
   tC = (40 - FirstDig) Mod 4
   If tC = 3 Then tC = tC + 1
   If tC > 1 Then tC = tC + 1
        
   temp = y Mod 100
   tD = (temp + temp \ 4) Mod 7
    
   tE = ((20 - tB - tC - tD) Mod 7) + 1
   d = tA + tE

'return the date
   If d > 31 Then
      d = d - 31
      m = 4
   Else
      m = 3
   End If

End Sub

INDEX

 


If you have any questions regarding the information presented here,
please e-mail Ron Mallen at rwmallen@chariot.net.au


This disclaimer applies to this document:

If you are using these dates to plan travel, meetings, or for any use requiring the expenditure of money, time, or other resources, please consult other sources to verify the dates of Easter holidays.   Neither R. W. Mallen or anyone who owns the hardware or manages the host machines of this home page, or the Astronomical Society of South Australia, nor anyone who has contributed any information that has been used in this document, may be held financially responsible, or responsible in any way, if these dates are incorrectly calculated or applied.   The user assumes full responsibility for the consequences of using this information.