Doomsday rule


Definition: An algorithm to find the day of the week for any date. It is simple enough to memorize and do mentally.

See also Zeller's congruence.

Note: Invented sometime before January 1976 by John Horton Conway, the mathematician who also invented the computer Game of Life.

Author: PEB

More information

Explanation, examples, origin, and links; a summary of the International Standard Date and Time Notation ISO 8601.

Go to the Dictionary of Algorithms and Data Structures home page.

If you have suggestions, corrections, or comments, please get in touch with Paul Black.

Entry modified 17 December 2004.
HTML page formatted Tue Jan 16 10:34:44 2018.

Cite this as:
Paul E. Black, "Doomsday rule", in Dictionary of Algorithms and Data Structures [online], Vreda Pieterse and Paul E. Black, eds. 17 December 2004. (accessed TODAY) Available from: