When is Paschal?

The Paschal feast, celebrating the resurrection of Jesus Christ, is the most important holy day in the Christian calendar, but it’s also a moving feast (it doesn’t have a fixed day it is held on). Worse, it’s the feast that many other feasts are based on¹

Worse, the church cannot agree as to when this is. Despite how trivial this distinction may seem to be, many see it as a vital distinction between the true church and the wayward (and even for those who don’t care so much, it’s a serious irritant). There are four main methodologies - though in Britain you’re usually only going to run into the first two:²

• Latercus used in the church in Britain and Ireland. An old method of calculating the date follows an 84 year cycle based on the Jewish lunar-based calculations for the Passover feast, but with modifications to ensure the Paschal feast falls after the equinox and on a Sunday (as implied by the Synoptic Gospels) even if this shifts the date on the Jewish calendar by a few days.
• The Alexandrian Computus used by the church in Rome. A 19-year cycle based on the enneadecaeteris - or 19 year cycle - of when lunar and solar days can be matched up. Calculated in Alexandria and acceptable to the Council of Nicaea’s rulings on the matter: not dependent on checking each year on the Jewish calendar, always on a Sunday, and after the spring equinox.
• The Victorian Computus by Victorius of Aquitaine. An attempt to reconcile the Latercus and the then still nascent Alexandrian Computus into a 532 year cycle.
• Quartodecimanism which means “fourteenth-day-ism” and was the historical simplest stance. The strategy here was to find a Jewish community to figure out when the month of Nisan was³ and then hold the date exactly on the 14th day.

Paschal will fall on the following dates⁴ each of the years of the campaign (in the Julian Calendar - bolded entries are computed the same by both the Latercus and Alexandrian Computus):

(Year)	Latercus	Alexandrian Computus	Victorian Computus	Quartodeciman
476	28 March	28 March	28 March	26 March
477	17 April	17 April	17 April	13 April
478	2 April	9 April	2 April	3 April
479	22 April	25 March	27 March	23 April
480	13 April	13 April	15 April	9 April
481	29 March	5 April	31 March	30 March
482	18 April	25 April	20 April	19 March
483	10 April	10 April	12 April	8 April
484	1 April	1 April	27 March	26 March
485	14 April	21 April	16 April	15 April
486	6 April	6 April	8 April	4 April
487	29 March	29 March	23 March	25 March
488	17 April	17 April	12 April	11 April
489	2 April	2 April	2 April	31 March
490	22 April	25 March	22 April	21 March
491	14 April	14 April	7 April	10 April
492	29 March	5 April	31 March	28 March
493	18 April	18 April	18 April	17 March
494	10 April	10 April	3 April	6 April
495	26 March	26 March	26 March	27 March
496	7 April	14 April	14 April	13 April
497	6 April	6 April	8 April	2 April
498	19 April	29 March	22 March	23 March
499	11 April	11 April	11 April	10 April
500	2 April	2 April	2 April	29 March
501	22 April	22 April	22 April	19 March
502	7 April	14 April	7 April	8 April
503	30 March	30 March	30 March	28 March
504	18 April	18 April	18 April	14 April
505	3 April	10 April	3 April	4 April
506	26 March	26 March	26 March	24 March
507	15 April	15 April	15 April	13 April
508	30 March	6 April	30 March	31 March
509	19 April	22 March	29 March	20 March
510	11 April	11 April	18 April	9 April
511	27 March	3 April	3 April	30 March
512	15 April	22 April	22 April	17 April
513	7 April	7 April	14 April	5 April
514	30 March	30 March	30 March	26 March
515	12 April	19 April	19 April	13 April
516	3 April	3 April	10 April	1 April
517	26 March	26 March	26 March	22 March
518	15 April	15 April	15 April	11 April
519	31 March	31 March	7 April	30 March
520	19 April	19 April	26 April	18 April
521	11 April	11 April	11 April	7 April
522	27 March	3 April	3 April	28 March
523	16 April	16 April	23 April	15 April
524	7 April	7 April	7 April	3 April
525	20 April	30 March	30 March	24 March
526	12 April	19 April	19 April	13 April
527	4 April	4 April	4 April	2 April
528	23 April	26 March	26 March	20 March
529	8 April	15 April	15 April	9 April
530	31 March	31 March	7 April	29 March
531	20 April	20 April	27 April	19 March
532	4 April	11 April	11 April	5 April
533	27 March	27 March	3 April	25 March
534	16 April	16 April	23 April	14 April
535	1 April	8 April	8 April	2 April
536	20 April	23 March	30 March	22 March
537	12 April	12 April	19 April	10 April
538	28 March	4 April	4 April	31 March
539	17 April	24 April	27 March	19 March
540	8 April	8 April	15 April	6 April
541	31 March	31 March	31 March	27 March
542	13 April	20 April	20 April	14 April
543	5 April	5 April	12 April	4 April
544	27 March	27 March	27 March	23 March
545	16 April	16 April	16 April	12 April
546	1 April	8 April	8 April	2 April
547	21 April	24 March	24 March	22 March
548	12 April	12 April	12 April	8 April
549	28 March	4 April	4 April	29 March
550	17 April	24 April	24 April	18 March
551	9 April	9 April	9 April	5 April
552	21 April	31 March	31 March	25 March
553	13 April	20 April	20 April	14 April
554	5 April	5 April	5 April	3 April
555	18 April	28 March	28 March	22 March
556	9 April	16 April	16 April	10 April
557	1 April	1 April	8 April	30 March
558	21 April	21 April	24 March	20 March
559	6 April	14 April	14 April	7 April
560	28 March	28 March	4 April	26 March

Footnotes

1. Such as the holy day of Pentecost held 50 days afterwards - the Greek Pentēkostē literally means “fiftieth” ↩

2. And run into the conflict between the two - because picking which day you celebrate on can be a religious-political decision (or just a source of confusion). ↩

3. Because the Hebrew calendar, being a lunar calculation, can shift compared to the Julian calendar and people have to make decisions about when to shift things to keep things smooth and not slowly drift too much - so there’s no way to calculate this exactly. ↩

4. Don’t use this as a scholarly resource - based on collected calculations previous players have made and my own poor attempts to calculate the dates. ↩