Calculation of Easter Sunday online for year 1980
| Item | Formula | Result |
|---|---|---|
| Golden number | gn = (year % 19) + 1 | 5 |
| Julian epact | je = 11 × gn % 30 | 25 |
| Century | ce = year / 100 + 1 | 20 |
| Solar correction | sc = 3 × (ce - 16) / 4 | 3 |
| Lunar correction | lc = 8 × (ce - 15) / 25 | 1 |
| Gregorian epact | ge = (je - 10 - sc + lc) % 30 | 13 |
| March date of Ecclesiastical full moon (Click here for show conversion table) | for ge <= 23: fm = 44 - ge | 31 |
| for ge = 24: fm = 49 | ||
| for ge = 25 and gn < 12: fm = 49 | ||
| for ge = 25 and gn >= 12: fm = 48 | ||
| for ge >= 26: fm = 74 - ge | ||
| date of Ecclesiastical full moon | March 31 | |
| Gregorian correction | gc = 10 + sc | 13 |
| Day of week for Ecclesiastical full moon The number 0 is Sunday, 1 is Monday, and so on until 6, which is Saturday | dfm = (year + year / 4 - gc + fm) % 7 | 1 |
| March date of the first Sunday after the Ecclesiastical full moon | es = fm + (7 - dfm) | 37 |
| Easter Sunday falls on the first Sunday after the Ecclesiastical full moon | April 6 | |
| Gregorian epact | Ecclesiastical full moon |
|---|---|
| 23 | March 21 |
| 22 | March 22 |
| 21 | March 23 |
| 20 | March 24 |
| 19 | March 25 |
| 18 | March 26 |
| 17 | March 27 |
| 16 | March 28 |
| 15 | March 29 |
| 14 | March 30 |
| 13 | March 31 |
| 12 | April 1 |
| 11 | April 2 |
| 10 | April 3 |
| 9 | April 4 |
| 8 | April 5 |
| 7 | April 6 |
| 6 | April 7 |
| 5 | April 8 |
| 4 | April 9 |
| 3 | April 10 |
| 2 | April 11 |
| 1 | April 12 |
| 0 | April 13 |
| 29 | April 14 |
| 28 | April 15 |
| 27 | April 16 |
| 26 | April 17 |
| 25/25 | April 17/18 |
| 24 | April 18 |
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