French Republican Calendar Converter

The French Republican Calendar Converter

If you've ever come across a date like "9 Thermidor An II" and thought, “What on earth is that?”—this tool is for you. The French Republican Calendar Converter helps you easily switch between standard Gregorian dates and the short-lived, revolutionary French calendar used from 1793 to 1805.

What this converter actually does

This isn't your typical timezone tool. Instead, it's a historical calendar translator, built to convert dates back and forth between two systems:

• Gregorian to Republican – Enter a date between September 22, 1792, and December 31, 1805, and see its equivalent in the French Republican calendar.
• Republican to Gregorian – Input a Republican day, month, and year, and get the corresponding Gregorian date.

Along the way, it also shows details like the day of the 10-day "décade" week, the revolutionary year, and even the symbolic dedication of that day (plants, Tools, animals, and so on).

Why someone might use this tool

If you're a historian, a researcher, a student, or just curious about the French Revolution, this tool saves time and confusion. French Revolutionary dates show up in everything from history books to museum plaques—and Googling every one of them is a pain. This tool makes the translation instant and visual, with no extra digging.

How to use it—step by step

Converting a Gregorian date to Republican

1. Pick a date using the calendar input (only dates between 1792-09-22 and 1805-12-31 are accepted).
2. Select your time zone from the dropdown menu. (It won’t affect the calendar math, but it will update how the Gregorian date appears.)
3. Make sure the “Gregorian to Republican” option is selected (it is by default).
4. Click "Convert Calendar"—or just change the date and it will auto-convert.
5. See your result: the Republican date, the décade day (like “Quintidi”), and the symbolic dedication (like “Dedicated to an animal”).

Converting a Republican date to Gregorian

1. Switch to “Republican to Gregorian.” This will reveal three input fields: day, month, and year.
2. Enter the Republican date. Remember, months have 30 days (except the 13th month, which has 5 or 6 festival days).
3. Click “Convert Calendar,” or just enter all three parts—the result will appear automatically.
4. Your result will be the Gregorian equivalent, fully formatted with weekday and local time zone settings.

Extra features you might not notice at first

Live time and date display

In the lower-right panel, you'll see the current time and today’s Gregorian date updating in real-time. There's also a button to toggle between 12-hour and 24-hour clocks.

Visual feedback

Each time you run a conversion, the result panel gives a quick visual pop—just a subtle way to confirm the update happened.

French formatting included

The tool also shows a fully French-formatted version of the Republican date (like “Le 9ème jour du mois de Thermidor l’an II de la République Française”)—great if you’re working with original texts or just want to get the full vibe of Revolutionary France.

Auto-detection and smart input

If you change any input, the tool updates results instantly. No need to re-click anything after changing fields. If something’s missing or outside valid range, it clears the results or shows a helpful alert.

Things to watch out for

• Date limits: The converter only works for dates from 1792-09-22 to 1805-12-31, because that’s when the Republican calendar was actually in use.
• Sans-culottides (Month 13): This month only has 5 or 6 days, depending on whether the year was a leap year. The tool will warn you if you try to enter too many.
• Input formatting: If you're doing Republican-to-Gregorian, make sure to fill in all three fields—day, month, and year. Leaving any blank won't give you a result.

Keeping your dates straight, from past to present

Converting between calendars shouldn’t take a spreadsheet, a library, and half your afternoon. This French Republican Calendar Converter keeps it simple: type in a date, get your answer, and move on. Whether you're prepping a paper, checking a historical source, or just feeding your curiosity, it gets the job done fast—and with a little flair.