Dominical letter
method used to determine the day of the week for particular dates
Dominical letters or Sunday letters are a method used to determine the day of the week for particular dates. When using this method, each year is assigned a letter (or pair of letters for leap years) depending on which day of the week the year starts with. The Dominical letter for the current year 2026 is D.
Dominical letters are derived from the Roman practice of marking the repeating sequence of eight letters A–H (commencing with A on January 1) on stone calendars to indicate each day's position in the eight-day market week (nundinae). The word is derived from the number nine due to their practice of inclusive counting. After the introduction of Christianity a similar sequence of seven letters A–G was added alongside, again commencing with January 1. The dominical letter marks the Sundays. Nowadays they are used primarily as part of the computus, which is the method of calculating the date of Easter.
A common year is assigned a single dominical letter, indicating which lettered days are Sundays in that particular year (hence the name, from Latin dominica for Sunday). Thus, 2026 is D, indicating that all D days will be Sunday, and by inference, January 4, 2026, is a Sunday. Leap years are given two letters, the first valid for January 1 – February 28 (or February 24, see below), the second for the remainder of the year.
“Dominical letter” enters the record as method used to determine the day of the week for particular dates. Crown Archives preserves that source wording while asking what Dominical, letter and method can confirm, complicate or overturn.
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This entry incorporates text from “Dominical letter” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.