French Revolutionary Calendar

Ever wondered how the French Revolutionary Calendar worked?

French Republican Calendar

Began on September 22 1792. Total number of days 365, 12 months of 30 days. The remaining 5 days being devoted to festivals & vacations, fell from September 17 - 22. Leap years retained at same frequency as Gregorian calendar and added to festival days. 1st leap year was year 3 (extra day fell September 22nd 1795). Each 4 year period was known as a Franciade.

                Each 30 day month was divided into 3 periods of 10 days called décades, the last day of each décade being a rest day.

                      Republican - Gregorian Dates

                Months marked * + 1 day Gregorian during leap years: see notes below

                *Vendémiaire (vintage: September 22 - October 21)

                *Brumaire (mist: October 22 - November 20)

                *Frimaire (frost: November 21 - December 20)

                *Nivôse (snow: December 21 - January 19)

                *Pluviôse (rain: January 20 - February 18)

                *Ventôse (wind: February 19 - March 20)

                Germinal (seed-time: March 21 - April19)

                Floréal (blossom: April 20 - May 19)

                Prairial (meadow: May 20 - June 18)

                Messidor (harvest: June 18 - July 18)

                Thermidor (heat: July 19 - August 17)

                Fructidor (fruits: August 18 - September 16)

                Abandoned 1 January 1806

1999/2000 = 207. in Autumn. Care is needed in translating from one system to the other as their leap years were out of synch Year 3 was first leap year = 1794. Republican dates match Gregorian dates as above except in leap years as follows:

                A Republican leap year precedes a Gregorian leap year, and its intercalary is on September 22. Therefore the New Year (1re.Vendémiaire) starts on September 23 and all the dates in the table above are shifted forward one day until Ventôse 10 (February 29 [Gregorian intercalary]). Ventôse 11 will then be March 1st. and everything is back in step again.

                To find whether a Gregorian Year is a leap year: if it divisible by 4 it is a leap year, unless it is a centennial year (xx00) indivisible by 400. Therefore 1800 and 1900 were not leap years, 2000 is. The preceding September 22 will be where the calendars go out of synch, and the Gregorian intercalary restores things once more.