From the Dominical Letter one can determine the dates on which Sundays occur.
One can also determine the start of week number 1.
It is defined as the week in which the Sunday lies between January 4 and January 10.
Easter Sunday is the first Sunday after a given New Moon.
| day | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | A | D | D | G | B | E | G | C | F | A | D | F |
| 2 | B | E | E | A | C | F | A | D | G | B | E | G |
| 3 | C | F | F | B | D | G | B | E | A | C | F | A |
| 4 | D | G | G | C | E | A | C | F | B | D | G | B |
| 5 | E | A | A | D | F | B | D | G | C | E | A | C |
| 6 | F | B | B | E | G | C | E | A | D | F | B | D |
| 7 | G | C | C | F | A | D | F | B | E | G | C | E |
| 8 | A | D | D | G | B | E | G | C | F | A | D | F |
| 9 | B | E | E | A | C | F | A | D | G | B | E | G |
| 10 | C | F | F | B | D | G | B | E | A | C | F | A |
| 11 | D | G | G | C | E | A | C | F | B | D | G | B |
| 12 | E | A | A | D | F | B | D | G | C | E | A | C |
| 13 | F | B | B | E | G | C | E | A | D | F | B | D |
| 14 | G | C | C | F | A | D | F | B | E | G | C | E |
| 15 | A | D | D | G | B | E | G | C | F | A | D | F |
| 16 | B | E | E | A | C | F | A | D | G | B | E | G |
| 17 | C | F | F | B | D | G | B | E | A | C | F | A |
| 18 | D | G | G | C | E | A | C | F | B | D | G | B |
| 19 | E | A | A | D | F | B | D | G | C | E | A | C |
| 20 | F | B | B | E | G | C | E | A | D | F | B | D |
| 21 | G | C | C | F | A | D | F | B | E | G | C | E |
| 22 | A | D | D | G | B | E | G | C | F | A | D | F |
| 23 | B | E | E | A | C | F | A | D | G | B | E | G |
| 24 | C | F | F | B | D | G | B | E | A | C | F | A |
| 25 | D | G | G | C | E | A | C | F | B | D | G | B |
| 26 | E | A | A | D | F | B | D | G | C | E | A | C |
| 27 | F | B | B | E | G | C | E | A | D | F | B | D |
| 28 | G | C | C | F | A | D | F | B | E | G | C | E |
| 29 | A | (D) | D | G | B | E | G | C | F | A | D | F |
| 30 | B | E | A | C | F | A | D | G | B | E | G | |
| 31 | C | F | D | B | E | C | A | |||||
| day | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
For example: the first Sunday of the year 1999 (Dominical Letter C) is January 3,
so week 1 is from Monday 1999-01-04 to Sunday 1999-01-10.
The first Sunday after 1999-03-31 is 1999-04-04 (Easter).
For calculating Ascension and Pentecost, one can use the day numbers associated to dates.