doomsday, a Python code which is given the year, month and day of a date, and uses John Conway's doomsday algorithm to determine the corresponding day of the week.


The computer code and data files described and made available on this web page are distributed under the MIT license


doomsday is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.

Related Data and Programs:

dates, a dataset directory which contains lists of dates in various calendar systems.

weekday, a Python code which determines the day of the week for a given day.

weekday_zeller, a Python code which uses Zeller's congruence to determine the day of the week corresponding to a given date, such as 13 July 1989, Gregorian calendar, ... which was a Thursday.


  1. John Conway,
    Tomorrow is the Day After Doomsday,
    Volume 36, October 1973, pages 28-31.

Source Code:

Last revised on 21 January 2020.