The French Republican calendar (French: calendrier républicain français), also commonly called the French Revolutionary calendar (calendrier révolutionnaire français), was a calendar created and implemented during the French Revolution, and used by the French government for about 12 years from late 1793 to 1805, and for 18 days by the Paris Commune in 1871, and meant to replace the Gregorian calendar.^[1]

The calendar consisted of twelve 30-day months, each divided into three 10-day cycles similar to weeks, plus five or six intercalary days at the end to fill out the balance of a solar year. It was designed in part to remove all religious and royalist influences from the calendar, and it was part of a larger attempt at dechristianization and decimalisation in France (which also included decimal time of day, decimalisation of currency, and metrication). It was used in government records in France and other areas under French rule, including Belgium, Luxembourg, and parts of the Netherlands, Germany, Switzerland, Malta, and Italy.

The National Constituent Assembly at first intended to create a new calendar marking the "era of Liberty", beginning on 14 July 1789, the date of the Storming of the Bastille. However, on 2 January 1792 its successor the Legislative Assembly decided that Year IV of Liberty had begun the day before. Year I had therefore begun on 1 January 1789.

On 21 September 1792, the French First Republic was proclaimed, and the new National Convention decided that 1792 was to be known as Year I of the French Republic. It decreed on 2 January 1793 that Year II of the Republic had begun the day before. However, the new calendar as adopted by the Convention in October 1793 made 22 September 1792 the first day of Year I.

Ultimately, the calendar came to commemorate the Republic, and not the Revolution. The Common Era, commemorating the birth of Jesus Christ, was abolished and replaced with l'ère républicaine, the Republican Era, signifying the "age of reason" overcoming superstition, as part of the campaign of dechristianization.

The First Republic ended with the coronation of Napoleon I as Emperor on 11 Frimaire, Year XIII, or 2 December 1804. Despite this, the republican calendar continued to be used until 1 January 1806, when Napoleon declared it abolished. It was briefly used again for a few weeks of the Paris Commune, in May 1871.

The prominent atheist essayist and philosopher Sylvain Maréchal published the first edition of his Almanach des Honnêtes-gens (Almanac of Honest People) in 1788.^[2] The first month in the almanac is "Mars, ou Princeps" (March, or First), the last month is "Février, ou Duodécembre" (February, or Twelfth). The lengths of the months are the same as those in the Gregorian calendar; however, the 10th, 20th, and 30th days are singled out of each month as the end of a décade (group of ten days). Individual days were assigned, instead of to the traditional saints, to people noteworthy for mostly secular achievements. Later editions of the almanac would switch to the Republican Calendar.^[3]

The days of the French Revolution and Republic saw many efforts to sweep away various trappings of the Ancien Régime (the old feudal monarchy); some of these were more successful than others. The new Republican government sought to institute, among other reforms, a new social and legal system, a new system of weights and measures (which became the metric system), and a new calendar.

Amid nostalgia for the ancient Roman Republic, the theories of the Age of Enlightenment were at their peak, and the devisers of the new systems looked to nature for their inspiration. Natural constants, multiples of ten, and Latin as well as Ancient Greek derivations formed the fundamental blocks from which the new systems were built.

The new calendar was created by a commission under the direction of the politician Gilbert Romme seconded by Claude Joseph Ferry [fr] and Charles-François Dupuis. They associated with their work the chemist Louis-Bernard Guyton de Morveau, the mathematician and astronomer Joseph-Louis Lagrange, the astronomer Jérôme Lalande, the mathematician Gaspard Monge, the astronomer and naval geographer Alexandre Guy Pingré, and the poet, actor and playwright Fabre d'Églantine, who invented the names of the months, with the help of André Thouin, gardener at the Jardin des plantes of the Muséum National d'Histoire Naturelle in Paris. As the rapporteur of the commission, Charles-Gilbert Romme presented the new calendar to the Jacobin-controlled National Convention on 23 September 1793, which adopted it on 24 October 1793 and also extended it proleptically to its epoch of 22 September 1792. It is because of his position as rapporteur of the commission that the creation of the republican calendar is attributed to Romme.^[4]

The calendar is frequently named the "French Revolutionary Calendar" because it was created during the Revolution, but this is a slight misnomer. In France, it is known as the calendrier républicain as well as the calendrier révolutionnaire. There was initially a debate as to whether the calendar should celebrate the Great Revolution, which began in July 1789, or the Republic, which was established in 1792.^[5] Immediately following 14 July 1789, papers and pamphlets started calling 1789 year I of Liberty and the following years II and III. It was in 1792, with the practical problem of dating financial transactions, that the legislative assembly was confronted with the problem of the calendar. Originally, the choice of epoch was either 1 January 1789 or 14 July 1789. After some hesitation the assembly decided on 2 January 1792 that all official documents would use the "era of Liberty" and that the year IV of Liberty started on 1 January 1792. This usage was modified on 22 September 1792 when the Republic was proclaimed and the Convention decided that all public documents would be dated Year I of the French Republic. The decree of 2 January 1793 stipulated that the year II of the Republic began on 1 January 1793; this was revoked with the introduction of the new calendar, which set 22 September 1793 as the beginning of year II. The establishment of the Republic was used as the epochal date for the calendar; therefore, the calendar commemorates the Republic, and not the Revolution.

French coins of the period naturally used this calendar. Many show the year (French: an) in Arabic numbers, although Roman numerals were used on some issues. Year 11 coins typically have a XI date to avoid confusion with the Roman II.

The French Revolution is usually considered to have ended with the coup of 18 Brumaire, Year VIII (9 November 1799), the coup d'état of Napoleon Bonaparte against the established constitutional regime of the Directoire.

The Concordat of 1801 re-established the Roman Catholic Church as an official institution in France, although not as the state religion of France. The concordat took effect from Easter Sunday, 28 Germinal, Year XI (8 April 1802); it restored the names of the days of the week to the ones from the Gregorian calendar, and fixed Sunday as the official day of rest and religious celebration.^[6] However, the other attributes of the republican calendar, the months, and years, remained as they were.

The French Republic ended with the coronation of Napoleon as Empereur des Français (Emperor of the French) on 11 Frimaire, Year XIII (2 December 1804), but the republican calendar would remain in place for another year. Napoleon finally abolished the republican calendar with effect from 1 January 1806 (the day after 10 Nivôse Year XIV), a little over twelve years after its introduction. It was, however, used again briefly in the Journal officiel for some dates during a short period of the Paris Commune, 6–23 May 1871 (16 Floréal–3 Prairial Year LXXIX).^[7]

Years appear in writing as Roman numerals (usually), with epoch 22 September 1792, the beginning of the "Republican Era" (the day the French First Republic was proclaimed, one day after the Convention abolished the monarchy). As a result, Roman Numeral I indicates the first year of the republic, that is, the year before the calendar actually came into use. By law, the beginning of each year was set at midnight, beginning on the day the apparent autumnal equinox falls at the Paris Observatory.

There were twelve months, each divided into three ten-day weeks called décades. The tenth day, décadi, replaced Sunday as the day of rest and festivity. The five or six extra days needed to approximate the solar or tropical year were placed after the final month of each year and called complementary days. This arrangement was an almost exact copy of the calendar used by the Ancient Egyptians, though in their case the year did not begin and end on the autumnal equinox.

A period of four years ending on a leap day was to be called a "Franciade". The name "Olympique" was originally proposed^[8] but changed to Franciade to commemorate the fact that it had taken the revolution four years to establish a republican government in France.^[9]

The leap year was called Sextile, an allusion to the "bissextile" leap years of the Julian and Gregorian calendars, because it contained a sixth complementary day.

Each day in the Republican Calendar was divided into ten hours, each hour into 100 decimal minutes, and each decimal minute into 100 decimal seconds. Thus an hour was 144 conventional minutes (2.4 times as long as a conventional hour), a minute was 86.4 conventional seconds (44% longer than a conventional minute), and a second was 0.864 conventional seconds (13.6% shorter than a conventional second).

Clocks were manufactured to display this decimal time, but it did not catch on. Mandatory use of decimal time was officially suspended 7 April 1795, although some cities continued to use decimal time as late as 1801.^[10]

The numbering of years in the Republican Calendar by Roman numerals ran counter to this general decimalization tendency.

The Republican calendar year began the day the autumnal equinox occurred in Paris, and had twelve months of 30 days each, which were given new names based on nature, principally having to do with the prevailing weather in and around Paris and sometimes evoking the Medieval Labours of the Months. The extra five or six days in the year were not given a month designation, but considered Sansculottides or Complementary Days.

• Autumn:
  • Vendémiaire (from French vendange, which means 'grape harvest', derived from Latin vindemia 'vintage'), starting 22, 23, or 24 September
  • Brumaire (from French brume 'mist', from Latin brūma 'winter solstice; winter; winter cold'), starting 22, 23, or 24 October
  • Frimaire (from French frimas 'frost'), starting 21, 22, or 23 November
• Winter:
  • Nivôse (from Latin nivosus 'snowy'), starting 21, 22, or 23 December
  • Pluviôse (from French pluvieux, derived from Latin pluvius 'rainy'), starting 20, 21, or 22 January
  • Ventôse (from French venteux, derived from Latin ventosus 'windy'), starting 19, 20, or 21 February
• Spring:
  • Germinal (from French germination), starting 21 or 22 March
  • Floréal (from French fleur, derived from Latin flos 'flower'), starting 20 or 21 April
  • Prairial (from French prairie 'meadow'), starting 20 or 21 May
• Summer:
  • Messidor (from Latin messis 'harvest'), starting 19 or 20 June
  • Thermidor (from Greek θέρμη, thermē, 'summer heat'), starting 19 or 20 July; on many printed calendars of Year II (1793–94), the month of Thermidor was named Fervidor (from Latin fervidus, "burning hot")
  • Fructidor (from Latin fructus 'fruit'), starting 18 or 19 August

Most of the month names were new words coined from French, Latin, or Greek. The endings of the names are grouped by season. -dor comes from δῶρον, dō̂ron means 'giving' in Greek.^[11]

In Britain, a contemporary wit mocked the Republican Calendar by calling the months: Wheezy, Sneezy, and Freezy; Slippy, Drippy, and Nippy; Showery, Flowery, and Bowery; Hoppy, Croppy, and Poppy.^[12][13] The historian Thomas Carlyle suggested somewhat more serious English names in his 1837 work The French Revolution: A History,^[11] namely Vintagearious, Fogarious, Frostarious, Snowous, Rainous, Windous, Buddal, Floweral, Meadowal, Reapidor, Heatidor, and Fruitidor. Like the French originals, they are neologisms suggesting a meaning related to the season.

The month is divided into three décades or "weeks" of ten days each, named:

• primidi (first day)
• duodi (second day)
• tridi (third day)
• quartidi (fourth day)
• quintidi (fifth day)
• sextidi (sixth day)
• septidi (seventh day)
• octidi (eighth day)
• nonidi (ninth day)
• décadi (tenth day)

Décadis became official days of rest instead of Sundays, in order to diminish the influence of the Roman Catholic Church. They were used for the festivals of a succession of new religions meant to replace Catholicism: the Cult of Reason, the Cult of the Supreme Being, the Decadary Cult, and Theophilanthropy. Christian holidays were officially abolished in favor of revolutionary holidays.

The law of 13 Fructidor year VI (August 30, 1798) required that marriages must only be celebrated on décadis. This law was applied from the 1st Vendémiaire year VII (September 22, 1798) to 28 Pluviôse year VIII (February 17, 1800).

Décades were abandoned at the changeover from Germinal to Floréal year X (20 to 21 April 1802), after Napoleon's Concordat with the Pope.^[14]

The Roman Catholic Church used a calendar of saints, which named each day of the year after an associated saint. To reduce the influence of the Church, Fabre d'Églantine introduced a Rural Calendar in which each day of the year had a unique name associated with the rural economy, stated to correspond to the time of year. Every décadi (ending in 0) was named after an agricultural tool. Each quintidi (ending in 5) was named for a common animal. The rest of the days were named for "grain, pasture, trees, roots, flowers, fruits" and other plants, except for the first month of winter, Nivôse, during which the rest of the days were named after minerals.^[15][16]

Our starting point was the idea of celebrating, through the calendar, the agricultural system, and of leading the nation back to it, marking the times and the fractions of the year by intelligible or visible signs taken from agriculture and the rural economy. (...)

As the calendar is something that we use so often, we must take advantage of this frequency of use to put elementary notions of agriculture before the people – to show the richness of nature, to make them love the fields, and to methodically show them the order of the influences of the heavens and of the products of the earth.

The priests assigned the commemoration of a so-called saint to each day of the year: this catalogue exhibited neither utility nor method; it was a collection of lies, of deceit or of charlatanism.

We thought that the nation, after having kicked out this canonised mob from its calendar, must replace it with the objects that make up the true riches of the nation, worthy objects not from a cult, but from agriculture – useful products of the soil, the tools that we use to cultivate it, and the domesticated animals, our faithful servants in these works; animals much more precious, without doubt, to the eye of reason, than the beatified skeletons pulled from the catacombs of Rome.

So we have arranged in the column of each month, the names of the real treasures of the rural economy. The grains, the pastures, the trees, the roots, the flowers, the fruits, the plants are arranged in the calendar, in such a way that the place and the day of the month that each product occupies is precisely the season and the day that Nature presents it to us.

— Fabre d'Églantine, "Rapport fait à la Convention nationale au nom de la Commission chargée de la confection du Calendrier",^[17] Imprimerie nationale, 1793

The following pictures, showing twelve allegories for the months, were illustrated by French painter Louis Lafitte (1779–1828), and engraved by Salvatore Tresca [fr] (1750–1815).^[18]

Vendémiaire (22/24 September – 21/23 October) 1 22 Sep Raisin (Grape) 2 23 Sep Safran (Saffron) 3 24 Sep Châtaigne (Chestnut) 4 25 Sep Colchique (Autumn Crocus) 5 26 Sep Cheval (Horse) 6 27 Sep Balsamine (Impatiens) 7 28 Sep Carotte (Carrot) 8 29 Sep Amaranthe (Amaranth) 9 30 Sep Panais (Parsnip) 10 1 Oct Cuve (Vat) 11 2 Oct Pomme de terre (Potato) 12 3 Oct Immortelle (Strawflower) 13 4 Oct Potiron (Winter squash) 14 5 Oct Réséda (Mignonette) 15 6 Oct Âne (Donkey) 16 7 Oct Belle de nuit (Four o'clock flower) 17 8 Oct Citrouille (Pumpkin) 18 9 Oct Sarrasin (Buckwheat) 19 10 Oct Tournesol (Sunflower) 20 11 Oct Pressoir (Wine-Press) 21 12 Oct Chanvre (Hemp) 22 13 Oct Pêche (Peach) 23 14 Oct Navet (Turnip) 24 15 Oct Amaryllis (Amaryllis) 25 16 Oct Bœuf (Ox) 26 17 Oct Aubergine (Eggplant) 27 18 Oct Piment (Chili pepper) 28 19 Oct Tomate (Tomato) 29 20 Oct Orge (Barley) 30 21 Oct Tonneau (Barrel)	Brumaire (22/24 October – 20/22 November) 1 22 Oct Pomme (Apple) 2 23 Oct Céleri (Celery) 3 24 Oct Poire (Pear) 4 25 Oct Betterave (Beetroot) 5 26 Oct Oie (Goose) 6 27 Oct Héliotrope (Heliotrope) 7 28 Oct Figue (Common fig) 8 29 Oct Scorsonère (Black Salsify) 9 30 Oct Alisier (Chequer Tree) 10 31 Oct Charrue (Plough) 11 1 Nov Salsifis (Salsify) 12 2 Nov Mâcre (Water caltrop) 13 3 Nov Topinambour (Jerusalem artichoke) 14 4 Nov Endive (Endive) 15 5 Nov Dindon (Turkey) 16 6 Nov Chervis (Skirret) 17 7 Nov Cresson (Watercress) 18 8 Nov Dentelaire (Leadworts) 19 9 Nov Grenade (Pomegranate) 20 10 Nov Herse (Harrow) 21 11 Nov Bacchante (Baccharis) 22 12 Nov Azerole (Azarole) 23 13 Nov Garance (Madder) 24 14 Nov Orange (Orange) 25 15 Nov Faisan (Pheasant) 26 16 Nov Pistache (Pistachio Nut) 27 17 Nov Macjonc (Tuberous pea) 28 18 Nov Coing (Quince) 29 19 Nov Cormier (Service tree) 30 20 Nov Rouleau (Roller)	Frimaire (21/23 November – 20/22 December) 1 21 Nov Raiponce (Rampion) 2 22 Nov Turneps (Cattle turnip) 3 23 Nov Chicorée (Chicory) 4 24 Nov Nèfle (Medlar) 5 25 Nov Cochon (Pig) 6 26 Nov Mâche (Lamb's lettuce) 7 27 Nov Chou-fleur (Cauliflower) 8 28 Nov Miel (Honey) 9 29 Nov Genièvre (Juniper) 10 30 Nov Pioche (Pickaxe) 11 1 Dec Cire (Wax) 12 2 Dec Raifort (Horseradish) 13 3 Dec Cèdre (Cedar tree) 14 4 Dec Sapin (Fir) 15 5 Dec Chevreuil (Roe deer) 16 6 Dec Ajonc (Gorse) 17 7 Dec Cyprès (Cypress Tree) 18 8 Dec Lierre (Ivy) 19 9 Dec Sabine (Savin Juniper) 20 10 Dec Hoyau (Fork hoe) 21 11 Dec Érable à sucre (Sugar Maple) 22 12 Dec Bruyère (Heather) 23 13 Dec Roseau (Reed plant) 24 14 Dec Oseille (Sorrel) 25 15 Dec Grillon (Cricket) 26 16 Dec Pignon (Pine nut) 27 17 Dec Liège (Cork) 28 18 Dec Truffe (Truffle) 29 19 Dec Olive (Olive) 30 20 Dec Pelle (Shovel)

Nivôse (21/23 December – 19/21 January) 1 21 Dec Tourbe (Peat) 2 22 Dec Houille (Coal) 3 23 Dec Bitume (Bitumen) 4 24 Dec Soufre (Sulphur) 5 25 Dec Chien (Dog) 6 26 Dec Lave (Lava) 7 27 Dec Terre végétale (Topsoil) 8 28 Dec Fumier (Manure) 9 29 Dec Salpêtre (Saltpeter) 10 30 Dec Fléau (Flail) 11 31 Dec Granit (Granite) 12 1 Jan Argile (Clay) 13 2 Jan Ardoise (Slate) 14 3 Jan Grès (Sandstone) 15 4 Jan Lapin (Rabbit) 16 5 Jan Silex (Flint) 17 6 Jan Marne (Marl) 18 7 Jan Pierre à chaux (Limestone) 19 8 Jan Marbre (Marble) 20 9 Jan Van (Winnowing fan) 21 10 Jan Pierre à plâtre (Gypsum) 22 11 Jan Sel (Salt) 23 12 Jan Fer (Iron) 24 13 Jan Cuivre (Copper) 25 14 Jan Chat (Cat) 26 15 Jan Étain (Tin) 27 16 Jan Plomb (Lead) 28 17 Jan Zinc (Zinc) 29 18 Jan Mercure (Mercury) 30 19 Jan Crible (Sieve)

Pluviôse (20/22 January – 18/20 February) 1 20 Jan Lauréole (Spurge-laurel) 2 21 Jan Mousse (Moss) 3 22 Jan Fragon (Butcher's Broom) 4 23 Jan Perce-neige (Snowdrop) 5 24 Jan Taureau (Bull) 6 25 Jan Laurier-thym (Laurustinus) 7 26 Jan Amadouvier (Tinder polypore) 8 27 Jan Mézéréon (Daphne mezereum) 9 28 Jan Peuplier (Poplar) 10 29 Jan Coignée (Axe) 11 30 Jan Ellébore (Hellebore) 12 31 Jan Brocoli (Broccoli) 13 1 Feb Laurier (Bay laurel) 14 2 Feb Avelinier (Filbert) 15 3 Feb Vache (Cow) 16 4 Feb Buis (Box Tree) 17 5 Feb Lichen (Lichen) 18 6 Feb If (Yew tree) 19 7 Feb Pulmonaire (Lungwort) 20 8 Feb Serpette (Billhook) 21 9 Feb Thlaspi (Pennycress) 22 10 Feb Thimelé (Rose Daphne) 23 11 Feb Chiendent (Couch grass) 24 12 Feb Trainasse (Common Knotgrass) 25 13 Feb Lièvre (Hare) 26 14 Feb Guède (Woad) 27 15 Feb Noisetier (Hazel) 28 16 Feb Cyclamen (Cyclamen) 29 17 Feb Chélidoine (Celandine) 30 18 Feb Traîneau (Sleigh)

Ventôse (19/21 February – 20/22 March) 1 19 Feb Tussilage (Coltsfoot) 2 20 Feb Cornouiller (Dogwood) 3 21 Feb Violier (Matthiola) 4 22 Feb Troène (Privet) 5 23 Feb Bouc (Billygoat) 6 24 Feb Asaret (Wild Ginger) 7 25 Feb Alaterne (Italian Buckthorn) 8 26 Feb Violette (Violet) 9 27 Feb Marceau (Goat Willow) 10 28 Feb Bêche (Spade) 11 1 Mar Narcisse (Narcissus) 12 2 Mar Orme (Elm) 13 3 Mar Fumeterre (Common fumitory) 14 4 Mar Vélar (Hedge mustard) 15 5 Mar Chèvre (Goat) 16 6 Mar Épinard (Spinach) 17 7 Mar Doronic (Doronicum) 18 8 Mar Mouron (Pimpernel) 19 9 Mar Cerfeuil (Chervil) 20 10 Mar Cordeau (Twine) 21 11 Mar Mandragore (Mandrake) 22 12 Mar Persil (Parsley) 23 13 Mar Cochléaria (Scurvy-grass) 24 14 Mar Pâquerette (Daisy) 25 15 Mar Thon (Tuna) 26 16 Mar Pissenlit (Dandelion) 27 17 Mar Sylvie (Wood Anemone) 28 18 Mar Capillaire (Maidenhair fern) 29 19 Mar Frêne (Ash tree) 30 20 Mar Plantoir (Dibber)

Germinal (21/23 March – 19/21 April) 1 21 Mar Primevère (Primrose) 2 22 Mar Platane (Plane Tree) 3 23 Mar Asperge (Asparagus) 4 24 Mar Tulipe (Tulip) 5 25 Mar Poule (Hen) 6 26 Mar Bette (Chard) 7 27 Mar Bouleau (Birch) 8 28 Mar Jonquille (Daffodil) 9 29 Mar Aulne (Alder) 10 30 Mar Couvoir (Incubator) 11 31 Mar Pervenche (Periwinkle) 12 1 Apr Charme (Hornbeam) 13 2 Apr Morille (Morel) 14 3 Apr Hêtre (Beech Tree) 15 4 Apr Abeille (Bee) 16 5 Apr Laitue (Lettuce) 17 6 Apr Mélèze (Larch) 18 7 Apr Ciguë (Hemlock) 19 8 Apr Radis (Radish) 20 9 Apr Ruche (Beehive) 21 10 Apr Gainier (Judas tree) 22 11 Apr Romaine (Romaine lettuce) 23 12 Apr Marronnier (Horse chestnut) 24 13 Apr Roquette (Arugula or Rocket) 25 14 Apr Pigeon (Pigeon) 26 15 Apr Lilas (Lilac) 27 16 Apr Anémone (Anemone) 28 17 Apr Pensée (Pansy) 29 18 Apr Myrtille (Bilberry) 30 19 Apr Greffoir (Grafting knife)

Floréal (20/22 April – 19/21 May) 1 20 Apr Rose (Rose) 2 21 Apr Chêne (Oak Tree) 3 22 Apr Fougère (Fern) 4 23 Apr Aubépine (Hawthorn) 5 24 Apr Rossignol (Nightingale) 6 25 Apr Ancolie (Common Columbine) 7 26 Apr Muguet (Lily of the valley) 8 27 Apr Champignon (Button mushroom) 9 28 Apr Hyacinthe (Hyacinth) 10 29 Apr Râteau (Rake) 11 30 Apr Rhubarbe (Rhubarb) 12 1 May Sainfoin (Sainfoin) 13 2 May Bâton d'or (Wallflower) 14 3 May Chamerisier (Fan Palm tree) 15 4 May Ver à soie (Silkworm) 16 5 May Consoude (Comfrey) 17 6 May Pimprenelle (Salad burnet) 18 7 May Corbeille d'or (Basket of Gold) 19 8 May Arroche (Orache) 20 9 May Sarcloir (Weeding hoe) 21 10 May Statice (Sea thrift) 22 11 May Fritillaire (Fritillary) 23 12 May Bourrache (Borage) 24 13 May Valériane (Valerian) 25 14 May Carpe (Carp) 26 15 May Fusain (Euonymus) 27 16 May Civette (Chives) 28 17 May Buglosse (Bugloss) 29 18 May Sénevé (White mustard) 30 19 May Houlette (Shepherd's crook)

Prairial (20/22 May – 18/20 June) 1 20 May Luzerne (Lucerne) 2 21 May Hémérocalle (Daylily) 3 22 May Trèfle (Clover) 4 23 May Angélique (Angelica) 5 24 May Canard (Duck) 6 25 May Mélisse (Lemon balm) 7 26 May Fromental (Oat grass) 8 27 May Martagon (Martagon lily) 9 28 May Serpolet (Wild Thyme) 10 29 May Faux (Scythe) 11 30 May Fraise (Strawberry) 12 31 May Bétoine (Betony) 13 1 Jun Pois (Pea) 14 2 Jun Acacia (Acacia) 15 3 Jun Caille (Quail) 16 4 Jun Œillet (Carnation) 17 5 Jun Sureau (Elderberry) 18 6 Jun Pavot (Poppy plant) 19 7 Jun Tilleul (Linden or Lime tree) 20 8 Jun Fourche (Pitchfork) 21 9 Jun Barbeau (Cornflower) 22 10 Jun Camomille (Camomile) 23 11 Jun Chèvrefeuille (Honeysuckle) 24 12 Jun Caille-lait (Bedstraw) 25 13 Jun Tanche (Tench) 26 14 Jun Jasmin (Jasmine) 27 15 Jun Verveine (Vervain) 28 16 Jun Thym (Thyme) 29 17 Jun Pivoine (Peony) 30 18 Jun Chariot (Handcart)

Messidor (19/21 June – 18/20 July) 1 19 Jun Seigle (Rye) 2 20 Jun Avoine (Oat) 3 21 Jun Oignon (Onion) 4 22 Jun Véronique (Speedwell) 5 23 Jun Mulet (Mule) 6 24 Jun Romarin (Rosemary) 7 25 Jun Concombre (Cucumber) 8 26 Jun Échalote (Shallot) 9 27 Jun Absinthe (Wormwood) 10 28 Jun Faucille (Sickle) 11 29 Jun Coriandre (Coriander) 12 30 Jun Artichaut (Artichoke) 13 1 Jul Girofle (Clove) 14 2 Jul Lavande (Lavender) 15 3 Jul Chamois (Chamois) 16 4 Jul Tabac (Tobacco) 17 5 Jul Groseille (Redcurrant) 18 6 Jul Gesse (Hairy Vetchling) 19 7 Jul Cerise (Cherry) 20 8 Jul Parc (Livestock pen) 21 9 Jul Menthe (Mint) 22 10 Jul Cumin (Cumin) 23 11 Jul Haricot (Bean) 24 12 Jul Orcanète (Alkanet) 25 13 Jul Pintade (Guineafowl) 26 14 Jul Sauge (Sage) 27 15 Jul Ail (Garlic) 28 16 Jul Vesce (Tare) 29 17 Jul Blé (Wheat) 30 18 Jul Chalémie (Shawm)

Thermidor (19/21 July – 17/19 August) 1 19 Jul Épeautre (Spelt) 2 20 Jul Bouillon blanc (Common mullein) 3 21 Jul Melon (Melon) 4 22 Jul Ivraie (Ryegrass) 5 23 Jul Bélier (Ram) 6 24 Jul Prêle (Horsetail) 7 25 Jul Armoise (Mugwort) 8 26 Jul Carthame (Safflower) 9 27 Jul Mûre (Blackberry) 10 28 Jul Arrosoir (Watering can) 11 29 Jul Panic (Foxtail millet) 12 30 Jul Salicorne (Common Glasswort) 13 31 Jul Abricot (Apricot) 14 1 Aug Basilic (Basil) 15 2 Aug Brebis (Ewe) 16 3 Aug Guimauve (Marshmallow) 17 4 Aug Lin (Flax) 18 5 Aug Amande (Almond) 19 6 Aug Gentiane (Gentian) 20 7 Aug Écluse (Lock) 21 8 Aug Carline (Carline thistle) 22 9 Aug Câprier (Caper) 23 10 Aug Lentille (Lentil) 24 11 Aug Aunée (Inula) 25 12 Aug Loutre (Otter) 26 13 Aug Myrte (Myrtle) 27 14 Aug Colza (Rapeseed) 28 15 Aug Lupin (Lupin) 29 16 Aug Coton (Cotton) 30 17 Aug Moulin (Mill)

Fructidor (18/20 August – 16/18 September) 1 18 Aug Prune (Plum) 2 19 Aug Millet (Millet) 3 20 Aug Lycoperdon (Puffball) 4 21 Aug Escourgeon (Six-row Barley) 5 22 Aug Saumon (Salmon) 6 23 Aug Tubéreuse (Tuberose) 7 24 Aug Sucrion (Winter Barley) 8 25 Aug Apocyn (Apocynum) 9 26 Aug Réglisse (Liquorice) 10 27 Aug Échelle (Ladder) 11 28 Aug Pastèque (Watermelon) 12 29 Aug Fenouil (Fennel) 13 30 Aug Épine vinette (European Barberry) 14 31 Aug Noix (Walnut) 15 1 Sep Truite (Trout) 16 2 Sep Citron (Lemon) 17 3 Sep Cardère (Teasel) 18 4 Sep Nerprun (Buckthorn) 19 5 Sep Tagette (Mexican Marigold) 20 6 Sep Hotte (Harvesting basket) 21 7 Sep Églantier (Wild Rose) 22 8 Sep Noisette (Hazelnut) 23 9 Sep Houblon (Hops) 24 10 Sep Sorgho (Sorghum) 25 11 Sep Écrevisse (Crayfish) 26 12 Sep Bigarade (Bitter orange) 27 13 Sep Verge d'or (Goldenrod) 28 14 Sep Maïs (Maize or Corn) 29 15 Sep Marron (Sweet Chestnut) 30 16 Sep Panier (Pack Basket)

Five extra days – six in leap years – were national holidays at the end of every year. These were originally known as les sans-culottides (after sans-culottes), but after year III (1795) as les jours complémentaires:

• 1st complementary day: La Fête de la Vertu, "Celebration of Virtue", on 17 or 18 September
• 2nd complementary day: La Fête du Génie, "Celebration of Talent", on 18 or 19 September
• 3rd complementary day: La Fête du Travail, "Celebration of Labour", on 19 or 20 September
• 4th complementary day: La Fête de l'Opinion, "Celebration of Convictions", on 20 or 21 September
• 5th complementary day: La Fête des Récompenses, "Celebration of Honours (Awards)", on 21 or 22 September
• 6th complementary day: La Fête de la Révolution, "Celebration of the Revolution", on 22 or 23 September (on leap years only)

Below are the Gregorian dates each year of the Republican Era (Ère Républicaine in French) began while the calendar was in effect.

Leap years are highlighted

• Extra (sextile) day inserted before date, due to previous leap year^[19]

The Republican Calendar was abolished in the year XIV (1805). After this year, there are two historically attested calendars which may be used to determine dates. Both calendars gave the same dates for years 17 to 52 (1808–1844), always beginning on 23 September, and it was suggested, but never adopted, that the reformed calendar be implemented during this period, before the Republican Calendar was abolished.

• Republican Calendar: The only legal calendar during the Republic. The first day of the year, 1 Vendémiaire, is always the day the autumn equinox occurs in Paris. About every 30 years, leap years are 5 years apart instead of 4, as happened between the leap years 15 and 20.^[20] The lengths of the first 524 years were calculated by Delambre.
• Reformed Republican Calendar: Following a proposal by Delambre in order to make leap years regular and predictable, with leap years being every year divisible by 4, except years divisible by 100 and not by 400. Years divisible by 4000 would also be ordinary years. Intended to be implemented in year 3, the reformed calendar was abandoned after the death of the head of the calendar committee, Gilbert Romme. This calendar also has the benefit that every year in the third century of the Republican Era (1992–2091) begins on 22 September.^[21]

Leap years are highlighted

• Extra (sextile) day inserted before date, due to previous leap year

For this calendar, Delambre's revised method of calculating leap years is used. Other methods may differ by one day. Time may be cached and therefore not accurate. Decimal time is according to Paris mean time, which is 9 minutes 21 seconds (6.49 decimal minutes) ahead of Greenwich Mean Time. (This tool calibrates the time, if calibration is desired.)

Year: 233	Month: Frimaire			Year: CCXXXIII
Day of the 10-day week (décade) Primidi Duodi Tridi Quartidi Quintidi Sextidi Septidi Octidi Nonidi Décadi	décade 7 1 Thursday 21 November 2024 2 Friday 22 November 2024 3 Saturday 23 November 2024 4 Sunday 24 November 2024 5 Monday 25 November 2024 6 Tuesday 26 November 2024 7 Wednesday 27 November 2024 8 Thursday 28 November 2024 9 Friday 29 November 2024 10 Saturday 30 November 2024	décade 8 11 Sunday 1 December 2024 12 Monday 2 December 2024 13 Tuesday 3 December 2024 14 Wednesday 4 December 2024 15 Thursday 5 December 2024 16 Friday 6 December 2024 17 Saturday 7 December 2024 18 Sunday 8 December 2024 19 Monday 9 December 2024 20 Tuesday 10 December 2024	décade 9 21 Wednesday 11 December 2024 22 Thursday 12 December 2024 23 Friday 13 December 2024 24 Saturday 14 December 2024 25 Sunday 15 December 2024 26 Monday 16 December 2024 27 Tuesday 17 December 2024 28 Wednesday 18 December 2024 29 Thursday 19 December 2024 30 Friday 20 December 2024	Decimal time - 10 h/day Paris 5h08m22s 12:02:30 Time of day - 24 h/day Greenwich

Leap years in the calendar are a point of great dispute, due to the contradicting statements in the establishing decree^[22] stating:

Each year begins at midnight, with the day on which the true autumnal equinox falls for the Paris Observatory.

and:

The four-year period, after which the addition of a day is usually necessary, is called the Franciade in memory of the revolution which, after four years of effort, led France to republican government. The fourth year of the Franciade is called Sextile.

These two specifications are incompatible, as leap years defined by the autumnal equinox in Paris do not recur on a regular four-year schedule. It was erroneously believed that one leap day would be skipped automatically every 129 years,^[23] on average, but actually five years would sometimes pass between leap years, about three times per century. Thus, the years III, VII, and XI were observed as leap years, and the years XV and XX were also planned as such, even though they were five years apart.

A fixed arithmetic rule for determining leap years was proposed by Jean Baptiste Joseph Delambre and presented to the Committee of Public Education by Gilbert Romme on 19 Floréal An III (8 May 1795). The proposed rule was to determine leap years by applying the rules of the Gregorian calendar to the years of the French Republic (years IV, VIII, XII, etc. were to be leap years) except that year 4000 (the last year of ten 400-year periods) should be a common year instead of a leap year. Shortly thereafter, Romme was sentenced to the guillotine and committed suicide, and the proposal was never adopted, although Jérôme Lalande repeatedly proposed it for a number of years. The proposal was intended to avoid uncertain future leap years caused by the inaccurate astronomical knowledge of the 1790s (even today, this statement is still valid due to the uncertainty in ΔT). In particular, the committee noted that the autumnal equinox of year 144 was predicted to occur at 11:59:40 pm local apparent time in Paris, which was closer to midnight than its inherent 3 to 4 minute uncertainty.

The calendar was abolished by an act dated 22 Fructidor an XIII (9 September 1805) and signed by Napoleon, which referred to a report by Michel-Louis-Étienne Regnaud de Saint-Jean d'Angély and Jean Joseph Mounier, listing two fundamental flaws.

1. The rule for leap years depended upon the uneven course of the sun, rather than fixed intervals, so that one must consult astronomers to determine when each year started, especially when the equinox happened close to midnight, as the exact moment could not be predicted with certainty.
2. Both the era and the beginning of the year were chosen to commemorate a historical event that occurred on the first day of autumn in France, whereas the other European nations began the year near the beginning of winter or spring, thus being impediments to the calendar's adoption in Europe and America, and even a part of the French nation, where the Gregorian calendar continued to be used, as it was required for religious purposes.

The report also noted that the 10-day décade was unpopular and had already been suppressed three years earlier in favor of the seven-day week, removing what was considered by some as one of the calendar's main benefits.^[24] The 10-day décade was unpopular with laborers because they received only one full day of rest out of ten, instead of one in seven, although they also got a half-day off on the fifth day (thus 36 full days and 36 half days in a year, for a total of 54 free days, compared to the usual 52 or 53 Sundays). It also, by design, conflicted with Sunday religious observances.

Another criticism of the calendar was that despite the poetic names of its months, they were tied to the climate and agriculture of metropolitan France and therefore not applicable to France's overseas territories.^[25]

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The "Coup of 18 Brumaire" or "Brumaire" was the coup d'état of Napoleon Bonaparte on 18 Brumaire An VIII (9 November 1799), which many historians consider to be the end of the French Revolution. Karl Marx's 1852 essay The Eighteenth Brumaire of Louis Bonaparte compares the coup d'état of 1851 of Louis Napoléon unfavorably to his uncle's earlier coup, with the statement "History repeats ... first as tragedy, then as farce".

Another famous revolutionary date is 9 Thermidor An II (27 July 1794), the date the Convention turned against Maximilien Robespierre, who, along with others associated with the Mountain, was guillotined the following day. Based on this event, the term "Thermidorian" entered the Marxist vocabulary as referring to revolutionaries who destroy the revolution from the inside and turn against its true aims. For example, Leon Trotsky and his followers used this term about Joseph Stalin.

Émile Zola's novel Germinal takes its name from the calendar's month of Germinal.

The seafood dish Lobster Thermidor was named after the 1891 play Thermidor, set during the Revolution.^[26][27]

The French frigates of the Floréal class all bear names of Republican months.

Wikimedia Commons has media related to French Republican Calendar.

Wikisource has original text related to this article:

Decree of the National Convention on the establishment of the Republican calendar

• Date converter for numerous calendars, including this one
• Simple converter from Gregorian date to Republican date and vice versa. Limited to the period during which the latter was actually in use.
• iCalendar files for the French Republican calendar, for use in Outlook, Google Calendar, etc.
• Dials & Symbols of the French revolution. The Republican Calendar and Decimal time.