Historical variabilty in prices of gold and silver.

[The Colonel]

If it helps - and it probably doesn't - I recall reading that at some point in classical history the difference in price between gold and silver varied enough from one end of the Mediterranean to the other that there was a thriving arbitrage trade going on simply exchanging the two metals and making a profit at each end...

[Fred Brackin]

Originally Posted by AlexanderHowl

W
Since a troy pound of silver is ~373 grams,t.

Please note that the values of $20,000 and $1000 for gold and silver per pound in Gurps will be avoirdupois lbs (7000 grains) and not Troy(5760 grains). introducing Troy measures will require significant care to avoid conversion errors.

If you want just one rate of exchange for gold to silver and want to see the historical evidence you're going to have to pick the evidence from just one place and time as your standard.

Perhaps you have some non-arbitrary rationale for such choosing but I would not.

[Hide]

Originally Posted by Lohengrin

Hello (...) what would be a good guideline for translating known relative prices of gold to silver to GURPS $?

In my opinion, this changes as you move around Tech-Level (TL).

I often try to set prices in ways players in my campaigns understand the worth of the goods. The easiest way for me, is building a small conversion table.

In my current fantasy campaign (TL3 to 4), I assumed that a GURPS $ equals the value of 1 Gold. For the sake of simplicity, the worth of coins in my settings is gold>silver>copper. Where copper represents 1/100 (one cent).

To adjust/comprehend the worth of money under TL3-4, I looked for items (in real history) that had as much relative worth as other items from our time.

Let’s say (for example) that swords, horses and beds in the medieval ages had the same worth of a car in our time. Swords are valuable in my setting, so I take swords as a reference and convert their GURPS $ value to (real-life) currency:

• A short-sword, is worth $ 400 GURPS.
• So, if an average car is about $ 40,000 USD.
• Then $ 1 G = $ 100 USD.

I often apply this conversion to items that are not listed in the books. For example, a BM hamburger combo is about $ 6 USD in the USA. If a player character decided to buy such hamburger in my setting, it would be $ 0.06 GURPS. This helps me to estimate the costs of rent, spending a night at an inn, or buying beer.

I also apply this rule to PC’s salaries or booty, if they ever earn money like this, I take the average wage in the US and convert it to GURPS $. This helps me to realize the worth of the stuff I provide players with.

For the stuff listed in the books, I preserve their price. This keeps the archer and the musketeers in check, helps warriors take care of their armor, and makes skills such as armory and scavenging quite worthy.

[AlexanderHowl]

Historically, a gold coins has been worth more than $1. In fact, the value of a gold sovereign (1500) was £1 and massed 15.55 grams (~15 grams of gold), and would have a labour value of around £7,000 (2019), probably the best compromise of value across times. A short sword was around 1/- at that time, around the equivalent of £350 (2019).

[Hide]

Originally Posted by AlexanderHowl

Historically, a gold coins has been worth more than $1 (...)

I must distinguish that in my suggestion I am not talking about the value of money/gold over the time. As I read in the OP, the objective is accomplishing a baseline to estimate the costs of goods and services not listed in the books, keeping them in accordance to what you already have. That's what I try to convey.

The value of goods and services is pretty subjective and changes over the time; for example, once upon a time salt was very valuable. It is not the most practical approach trying to achieve a baseline trough historical variability of gold and silver.

There's a number of reasons, but in general, to understand the economy of anachronistic/different societies you may need to study them deeply (let alone finding a unified reference).

For simplicity, all you should care about is whether bread is affordable or not.
What you need is “translating” the costs listed by GURPS to currency you understand.

For example, if you follow the suggestion I provided before (in which the sword is as expensive as the car), a white bread (20 oz.) is about 1 copper (which in the USA is about .90 cents).

If you earn $ 85 USD per day (about $ 31,000 USD per year, real median income in the USA), this means your PCs earn $ 26 GURPS.

[AlexanderHowl]

Nominal per capita income is $62,600, which should probably represent the earnings of an 'average' Status 0 individual in the USA. If you divide that by TL8 average income in GURPS, you end up with a x2 multiplier.