Or: More about French currency than you EVER wanted to know.
1 franc (= 1 livre) = 100 centimes.
1 sou = 1/20 of a franc = 5 centimes.
1 écu = 5 francs = 100 sous
1 louis d’or or gold Napoléon = 20 francs
Rule of thumb for exchange rates:
One British pound sterling = 25 francs, one Spanish escudo = 10 francs, one American dollar = 5 francs, one Russian ruble = 4 francs (in Russian-occupied Poland, one zloty = 0.6 francs), one Prussian thaler = 3.75 francs.
(These were relatively stable, since most countries were on the gold standard)
Standard types of coins
Throughout the early 19th century in France, gold coins were minted in denominations of 40 and 20 francs, and silver coins in denominations of 5 francs, 2 francs, 1 franc, 1/2 franc (50 centimes), 1/4 franc (25 centimes), and sometimes (in the Empire and early Restoration) 1/10 franc (the décime). Copper coins in denominations of 10, 5, and 1 centime were minted under the Consulate and continued to circulate all through the early 19th century.
The 5-franc coin was commonly called an écu, or sometimes a hundred-sou coin. 20-franc coins minted under the Empire were called gold Napoleons; under the Restoration and July Monarchy they were called louis d’or (gold louis). As far as I can tell, the 15-sou (75-centime) piece Cosette lost in the woods didn’t actually exist until the late 1840s.
Miscellaneous coin names
- Marius’ grandfather sends him sixty pistoles every six months. The pistole wasn’t actually a French coin; it was a name for the Spanish écu, or escudo, worth 10 francs.
- Deniers, liards, etc: were part of the Ancien Régime currency system, and even after decimalization the names stayed in use, if only to figuratively designate a tiny amount. (The sou was actually also a linguistic relic of the old system, and wasn’t officially part of French decimal currency; people were used to calculating prices in terms of sous, and since a sou was conveniently worth 5 cents, it had more staying power as an exact value that was part of daily life.) Technically, a denier was 1/12 of a sou, or 1/240 of a franc, or a little under half a centime, and a liard was 3 deniers, or 1/4 sou, or 1/80 (0.0125) franc, or one and a quarter centimes.
The Ancien Régime currency system
Was roughly equivalent to the pre-decimalization British currency system, although the French versions were worth substantially less. The basic units were the livre (which was also the word for ‘pound’ as a unit of weight), the sou or sol (shilling), and the denier (penny). 12 deniers to a sou, 20 sous to a livre. So a liard was basically a thruppenny bit. Coins in multiples of a livre were issued under the names écu and louis (or louis d’or), but their values were often redefined over the centuries and the name ‘louis’ could refer to assorted multiples of itself. Attempting to make sense of them is enough to make my head hurt, so unless you have to deal with higher-value coins in a fic set pre-1795, just stick to the post-decimalization values of louis and écu given above. As if that wasn’t bad enough, in the late Middle Ages and Renaissance there were two standards for the livre, the livre tournois and the livre parisis; the livre tournois, which eventually won out, was worth 4/5 of the livre parisis, which made for some fun conversions in accounting. (When is a shilling worth 15 pence? Oh, France.)
France switched to decimal currency in 1795. Generally, 1 livre = 1 franc, and the words were used more-or-less interchangeably, although the equivalences were a bit funky all through the Directory and the Consulate, and the minting of the new coins didn’t get underway until 1796. Some of the old coins stayed in circulation, apparently, well into the 19th century, but they would’ve become rarer and rarer as time went on.
Conversion to modern currency
Basically, don’t even try it. The relative prices of various commodities were all different in the early 19th century: rent and services were cheap, food and durable goods like clothing were expensive. It’s nearly impossible to construct any kind of meaningful exchange rate. The closest I’ll come is to say that you can get an extremely rough estimate by considering an early 19th century franc to be worth somewhere between 10 and 20 modern British pounds.