The date of Easter Sunday is commonly defined as the first Sunday that falls after the full moon, sometimes called the Easter or Paschal Full Moon, that occurs after the spring equinox. As the precise computation of the moments of the spring equinox and the astronomical full moon is complex and laborious the determination of Easter Sunday has always been based on a simplified method.
The date of the spring equinox is hereby fixed as 21 March and the ‘ecclesiastical’ full moon dates are obtained from a table based on the mean motions of the sun and the moon. The Easter Full Moon is the tabular full moon that occurs on or after 21 March and the first Sunday that occurs afterwards is Easter Sunday. The earliest possible date for Easter Sunday is thus 22 March, which can only occur when the Easter Full Moon falls on Saturday 21 March.
As the astronomical spring equinox can actually occur on 19, 20 or 21 March and the astronomical full moon can also fall a day earlier or later than its mean tabular date it sometimes happens that the Easter date, as computed from the true motions of the sun and the moon, differs from the date as determined from the ecclesiastical rules.
The following tables list the years between 1583 and 2500 when the dates of astronomical Easter Sunday and Gregorian Easter Sunday are different. The tables are based on Jean Meeus, Mathematical Astronomy Morsels (Richmond: Willmann-Bell, 1997), pp. 364–366 and Mathematical Astronomy Morsels V (Richmond: Willmann-Bell, 2009), p. 390. Also tabulated are the golden number (G) and the Easter date difference in weeks (Δw).
| Year | Easter Sunday | Year | Easter Sunday | |||||||
| Astronomical | Gregorian | G | Δw | Astronomical | Gregorian | G | Δw | |||
| 1590 | 25 March | 22 April | 14 | +4 | 1825 | 10 April | 3 April | 2 | –1 | |
| 1598 | 29 March | 22 March | 3 | –1 | 1829 | 26 April | 19 April | 6 | –1 | |
| 1609 | 26 April | 19 April | 14 | –1 | 1845 | 30 March | 23 March | 3 | –1 | |
| 1622 | 3 April | 27 March | 8 | –1 | 1876 | 9 April | 16 April | 15 | +1 | |
| 1629 | 8 April | 15 April | 15 | +1 | 1900 | 22 April | 15 April | 1 | –1 | |
| 1666 | 21 March | 25 April | 14 | +5 | 1903 | 19 April | 12 April | 4 | –1 | |
| 1685 | 25 March | 22 April | 14 | +4 | 1923 | 8 April | 1 April | 5 | –1 | |
| 1693 | 29 March | 22 March | 3 | –1 | 1924 | 23 March | 20 April | 6 | +4 | |
| 1700 | 4 April | 11 April | 10 | +1 | 1927 | 24 April | 17 April | 9 | –1 | |
| 1724 | 9 April | 16 April | 15 | +1 | 1943 | 28 March | 25 April | 6 | +4 | |
| 1744 | 29 March | 5 April | 16 | +1 | 1954 | 25 April | 18 April | 17 | –1 | |
| 1778 | 12 April | 19 April | 12 | +1 | 1962 | 25 March | 22 April | 6 | +4 | |
| 1798 | 1 April | 8 April | 13 | +1 | 1967 | 2 April | 26 March | 11 | –1 | |
| 1802 | 25 April | 18 April | 17 | –1 | 1974 | 7 April | 14 April | 18 | +1 | |
| 1818 | 29 March | 22 March | 14 | –1 | 1981 | 26 April | 19 April | 6 | –1 | |
| Year | Easter Sunday | Year | Easter Sunday | |||||||
| Astronomical | Gregorian | G | Δw | Astronomical | Gregorian | G | Δw | |||
| 2019 | 24 March | 21 April | 6 | +4 | 2296 | 22 March | 19 April | 17 | +4 | |
| 2038 | 28 March | 25 April | 6 | +4 | 2299 | 23 April | 16 April | 1 | –1 | |
| 2045 | 2 April | 9 April | 13 | +1 | 2316 | 9 April | 16 April | 18 | +1 | |
| 2049 | 25 April | 18 April | 17 | –1 | 2336 | 29 March | 5 April | 19 | +1 | |
| 2057 | 25 March | 22 April | 6 | +4 | 2339 | 2 April | 26 March | 3 | –1 | |
| 2069 | 7 April | 14 April | 18 | +1 | 2353 | 26 April | 22 March | 17 | –5 | |
| 2076 | 22 March | 19 April | 6 | +4 | 2372 | 23 April | 26 March | 17 | –4 | |
| 2089 | 27 March | 3 April | 9 | +1 | 2390 | 1 April | 8 April | 16 | +1 | |
| 2095 | 27 March | 24 April | 6 | +4 | 2394 | 24 April | 17 April | 1 | –1 | |
| 2096 | 8 April | 15 April | 7 | +1 | 2410 | 28 March | 25 April | 17 | +4 | |
| 2106 | 25 April | 18 April | 17 | –1 | 2417 | 9 April | 2 April | 5 | –1 | |
| 2114 | 25 March | 22 April | 6 | +4 | 2421 | 25 April | 18 April | 9 | –1 | |
| 2119 | 2 April | 26 March | 11 | –1 | 2429 | 25 March | 22 April | 17 | +4 | |
| 2133 | 22 March | 19 April | 6 | +4 | 2437 | 29 March | 22 March | 6 | –1 | |
| 2147 | 23 April | 16 April | 1 | –1 | 2448 | 22 March | 19 April | 17 | +4 | |
| 2150 | 19 April | 12 April | 4 | –1 | 2451 | 23 April | 16 April | 1 | –1 | |
| 2170 | 8 April | 1 April | 5 | –1 | 2467 | 27 March | 24 April | 17 | +4 | |
| 2171 | 24 March | 21 April | 6 | +4 | 2468 | 8 April | 15 April | 18 | +1 | |
| 2174 | 24 April | 17 April | 9 | –1 | 2471 | 12 April | 5 April | 2 | –1 | |
| 2190 | 28 March | 25 April | 6 | +4 | 2486 | 24 March | 21 April | 17 | +4 | |
| 2201 | 26 April | 19 April | 17 | –1 | 2488 | 28 March | 4 April | 19 | +1 | |
| 2221 | 8 April | 15 April | 18 | +1 | 2491 | 1 April | 25 March | 3 | –1 | |
| 2245 | 20 April | 13 April | 4 | –1 | 2492 | 20 April | 13 April | 4 | –1 | |
| 2277 | 25 March | 22 April | 17 | +4 | 2495 | 17 April | 10 April | 7 | –1 | |
According to the traditional Easter reckoning, both Dionysian and Gregorian, the extreme possible dates for Easter Sunday are 22 March and 25 April.
In the astronomical reckoning, however, Easter Sunday can occur as early as 21 March (as in 1666) and as late as 26 April (as in 1609, 1829, 1981, 2201 and 2353). Even 20 March is a possible date in the astronomical reckoning, when the spring equinox falls on 19 March and the full moon later on the same date (being a Saturday). However, in the period considered here (1583–2500) this never happens.