is a Python script I wrote for converting between the Gregorian and French republican calendars. The code is available here. It should work on any computer with a Python 2.5+ interpreter installed. If you use Linux or OS X it is very likely that Python is already installed. Python installers for Windows are available from


Several electronic conversion tools for the republican calendar already exist, but most are Web-based or run only on phones, and none that I could find works natively on Linux. I wanted a program that requires neither Internet access, nor emulation, nor a sophisticated phone.

In addition, none of the existing tools of which I'm aware is very useful for automated tasks (e.g., recursive conversion of a list of dates from one format to the other), which can do easily.

Usage accepts arguments in the following format:

day month year

day is a number between 1 and 31, month is the name of a Gregorian or French republican calendar month and year is a number between 1 and 1791 when entering republican dates, or between 1792 and 9999 for Gregorian dates. In all cases, the year must be entered with Arabic numerals; Roman numerals are not supported.

Sansculottides days can be entered in the format:

name-of-day year
Génie 2

The script will tolerate month and day names that are not properly capitalized or accented.


$ 22 September 1792
Republican date:  1 Vendémiaire Year 1
Gregorian date:  1792-09-22

$ 9 thermidor 2
Republican date:  9 Thermidor Year 2
Gregorian date:  1794-07-27

$ 19 September 1794
Republican date:  Day of Travail (sansculottide) Year 2
Gregorian date:  1794-09-19


This is a work in progress and there are some things that could be improved. In particular, I'd like to find time to add support for calculating names of normal republican days, and provide options for controlling output formatting and order. Some parts of the code could also be cleaned up, especially in the get_rep_date() function.

In addition, although the script accepts input for all years between 1 and 9999 (the upper limit of years supported by Python datetime functions), it ceases to provide very accurate conversions after around 1805, when the republican calendar was suppressed. To fix this, parts of the code would need to be rewritten to handle leap years better. For dates that fall within the years during which the calendar was actually used (not including under the Paris Commune of 1871), however, the output should be accurate.