I’m gonna rant a little here now. I don’t know why this particular thing bothered me enough this evening to rant about it, but I just feel the need.
I read a lot of fantasy novels. I love them. I cut my teeth on Lord of the Rings and Narnia. I read David Eddings in high school and all the other not particularly greats in high school. I bought every D&D novel I could get my hands on. Loved Codex Aleria. Tried really hard to love Song of Ice and Fire, but holy crap George, it’s okay if one nice thing happens every three hundred pages or so.
I am not bashing on fantasy here. We clear?
There’s this thing. When I pick up a new fantasy book, or when I hear one read in my critique group, I can tell really quickly whether the author learned most of his world-building from Dungeons & Dragons or not. Someone gets paid to do something. That thing is not “be a baron in my holdings” and the person is paid multiple gold pieces—sometimes hundreds of gold pieces.
A gold piece in the hazy middle-ages Europe of most Tolkien-derived fantasy worlds is worth (very roughly) fifty thousand dollars.
That’s a wildly inaccurate estimate, because the value of gold went up and down depending on how much gold was around, but for a big swath of time it’s how much a lord probably paid a knight for a year’s service.
If you hire a group of plucky adventurers to go raid your enemy’s base and you pay them 1000 GP, you could have hired a small army instead.
You can also tell who knows what gold is when you get to the scene where someone carries a bag of it. Here’s a quick experiment. Get a bag full of pennies. Pick it up. Now get another one, and another one about half full. Pick up all three bags. That’s roughly the weight of the first bag if it was gold coins. Gold is REALLY heavy.
Silver weighs about half of what gold does. (Atomic weight of 107.8 vs 196.9) It was also a much more reasonable currency. You bought things like manor houses and suits of full plate armor with gold coins. You paid your craftsmen and soldiers in silver. You paid your peasants in copper.
(Also, it’s really hard to do price comparisons between a pre-industrial and post-industrial society. Things cost more when they’re harder to make. So stuff like basic food stays pretty constant, while manufactured goods get less and less expensive over time. I’m carrying a knife I bought for the price of a cheap dinner for two that would have been a major expense for someone in the 12th century. In fact, it might not have been possible to make then.)
D&D also simplified the exchange rate a lot, making everything in multiples of 5 and 10. In the real world, coins were measured by weight, and thus tended to have values divisible by 4. (It’s easier to measure out half of something over and over again than to divide it into 10s.)
The British system, for a long time was 1 gold Pound = 20 silver Shillings = 240 copper Pence.
Also, coins were smaller than you think. A friend gave me two Roman Denarii (the equivalent of pence. When the widow gave her two mites, they were Denarii). Each one is smaller than my pinky nail.
(Wikipedia tells me the Denarius was originally silver, but gradually debased, reducing its value. See how easy it is to get this stuff right? I just needed to look up the plural of Denarius and I learned that Denarii were silver, not copper.)
So anyway, all this might not matter much in the grand scheme of things. If you create a fantasy world with wonky currency, only a handful of your readers are going to care. But it’s also not hard to get it right. You could put together a pretty functional price list and currency system after a day of poking around with Google. And yours doesn’t have to be strictly accurate. It just needs to be well thought out.
Gold is valuable because it’s pretty and rare. Silver is less valuable because it’s not quite as pretty and not quite as rare. Copper or bronze aren’t very valuable at all, and are mostly introduced because people need pocket change. (Although they might not have pockets)
Coins weren’t inherently valuable until fairly recent in history (in Europe). They were just conveniently sized pieces of precious metal. You could pay for something that cost a pound with an actual pound of gold, but you’d need a jeweler’s saw and a scale. And a merchant who had a scale would probably weigh your coins to make sure they weren’t debased if he could.
Getting this kind of detail right can also give you chances for drama in your story. How cool would it be if your hero slew the dragon, but could only get a fraction of the beast’s horde out of its cave? Now he’s got to figure out how to get the rest without anybody else finding the cave.
And what happens to the kingdom where he brings the gold? Remember, gold is valuable because it’s rare. If your hero hauls in the equivalent of the entire Roman treasury, he’s going to start an economic depression or an outright war.
Isn’t that way more fun than just another bar fight?