1 livre = 20 sous = 240 deniers. I’m relieved we switched to a base ten system. That’s a whole lot of math. In the Carolingian period, only the denier was an actual coin, livres and sous were accounting tricks.
Here’s something I was fascinated to find this week, in the book “La Vie Quotidienne dans l’Empire Carolingien,” by Pierre Riché, and maybe it’s just because my mind is on tax season.
This is a list of typical market prices in France in 794. Obviously things fluctuated year to year and location to location, but here at least, is a ballpark. There was a famine in 793 that drove up the price of everything. So in 794 the emperor published a list of market prices that necessities had to be sold for. That’s where at least some of this comes from.
The government did step in and control prices from time to time. To enforce the fixed maximum prices, it was for a long time apparently required by law to transact sales only during the day and with a witness.

1 hogshead of wheat = 6 deniers
1 sheep = 12-15 deniers

1 male slave = 144 deniers
Price fixing was made a more complicated endeavor by the fact that units of measure varied from region to region and time to time. A hogshead could be anywhere from 20 to 70 liters.
I don’t know why pricing is given here for male slaves but not for female. Maybe women’s values were more subjective? Or maybe the author just didn’t want to get into that.
M. Riché passed away last year, sadly. This is the first of his books I’ve read, but I’ll be ordering more. He did a fantastic job taking a huge amount of random information and compiling it into a dense but still very engaging (even funny) read.