This article is from the Calendars FAQ, by Claus Tondering email@example.com with numerous contributions by others.
A year consists of 365 or 366 days, divided into 12 months of 30 days
each, followed by 5 or 6 additional days. The months were:
(The second e in Vendemiaire and the e in Floreal carry an acute
accent. The o's in Nivose, Pluviose, and Ventose carry a circumflex
The year was not divided into weeks, instead each month was divided
into three "decades" of 10 days, of which the final day was a day of
rest. This was an attempt to de-Christianize the calendar, but it was
an unpopular move, because now there were 9 work days between each day
of rest, whereas the Gregorian Calendar had only 6 work days between
The ten days of each decade were called, respectively, Primidi, Duodi,
Tridi, Quartidi, Quintidi, Sextidi, Septidi, Octidi, Nonidi, Decadi.
The 5 or 6 additional days followed the last day of Fructidor and were
1. Fete de la vertu (Celebration of virtue)
2. Fete du genie (Celebration of genius)
3. Fete du travail (Celebration of labour)
4. Fete de l'opinion (Celebration of opinion)
5. Fete des recompenses (Celebration of rewards)
6. Jour de la revolution (Day of the revolution) (the leap day)
Each year was supposed to start on autumnal equinox (around 22
September), but this created problems as will be seen in section 7.3.