Converter for the french republican calendar, as a swift package

What's New



Adds support for the Romme variant.
Changes how options are set on FrenchRepublicanDate. The FrenchRepublicanDateOptions must be extended to conform to SaveableFrenchRepublicanDateOptions in order for FrenchRepublicanDate to use changeable options. It is the responsibility of the library user to persist those settings for the user.

French Republican Calendar Core

Version Française
For the app: iOS app source code

Swift Converter between the Gregorian Calendar and the French Republican Calendar. Fully tested and compliant with the original version.


  • iOS / watchOS app: view repo
  • WebAssembly web app: coming soon
  • Tests so you can see for yourself that only my implementation is correct 😤

Often, online converters are wrong : They either forget that 1800 and 1900 were sextils but not leap years, either forget 2000 was a leap year.
You can often see that by yourself by converting around March 1st of those years... My implementation is fully tested and doesn't have those issues.

All returned values are correct, until around the years 15.300 (in Gregorian), where the Republican to Gregorian conversion fails, because at that point, the first day of the Republican year and the first day of the Gregorian year happen at the same time.


  • Swift Tools 5.3.0
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Last updated: Sat Apr 01 2023 05:12:33 GMT-0500 (GMT-05:00)