Not simply a conversion of money, as even independent of inflation, the value of basics like bread and such change over time. I am reading "The Count of Monte Cristo" and a character has just remarked that 50,000 Francs is "a large sum, but not a fortune". Would this be, for example, enough to purchase a upper-middle class home in Paris at the time?
This Wikipedia article (in French) lists the annual salary in francs of several employees of Jacques Augustin Catherine Pajou in 1828, after his death, probably close enough to OP's time frame to be adequate:
- sa cuisinière [his cook] 350 francs;
- son domestique [his maid] 500 francs;
- son jardinier [his gardener] 700 francs;
Also listed is an inventory and assessment of three valuable items from the estate:
- deux médailles en argent pesant ensemble cinq kilogrammes huit cent soixante grammes sont prisées à raison de deux cents quatre francs cinquante centimes le kilogramme pour 1.201 f 30 [Two silver medals weighing five kilograms eight hundred and sixty grams are prized at the rate of two hundred and four francs fifty cents per kilogram for 1,201 f 30]
- Une médaille en or pesant cent quarante un gramme quarante-neuf centième est prisée 439 f 50. [A gold medal weighing one hundred forty one gram forty-nine hundred is prized 439 f 50.]