This is a follow up to my earlier post on historical coinage in general (and how it differed from the tons-of-gold decimal system in the Dungeons & Dragons rulebooks). Here, I offer some usable currency systems; they are based on historical models, though mostly somewhat simplified.
I have chosen realms and periods where the coinage was made of precious metal, fairly pure. Historically, most authorities went through periods when the precious metal content of the coinage was reduced. As a result, prices increased and a later government needed to restore the coinage (or, in more developed economies, to transition to representative money or fiat money) to stabilise the economy. But I leave it up to you whether to feature such episodes in your settings.
This is based on English currency from the 8th to 15th centuries, but also resembles several other western European currencies of the middle ages.
The main unit is the silver penny. Three hundred pennies weigh one modern pound. A penny might buy a day’s labour in the high middle ages, or you might pay fourpence late in the period.
The one-penny coin is the most common and may be the only denomination minted. For smaller amounts you can cut a penny in half or in quarters; this is sometimes done by the issuing moneyer, and the penny may be stamped with a symmetrical cross design to make this easier. For larger amounts you simply use multiple pennies.
You can say there are larger silver coins in multiples of the penny (such as 2 pence and 4 pence), and/or smaller coins in fractions of it (such as half and quarter), but in play it will be easiest just to track how many pence worth of silver that a character has. The coin denominations don’t affect the total value or weight.
You can also add gold coinage to the system. It would be simple but not very historical to have a gold coin the same weight as the penny and worth 10 pence, or a large gold coin weighing 30 to the pound and worth 100 pence.
If you are up for a non-decimal system, the historical units of account are the shilling (12 pence), the mark (160 pence or 13 shillings and fourpence) and the pound (240 pence or 20 shillings). Gold coins might then be a shilling weighing about the same as the penny (actually issued only briefly in the early middle ages, perhaps because such a small gold coin was fiddly and vulnerable to loss and wear) and/or a noble worth 80 pence (conveniently 2 nobles to the mark and 3 nobles to the pound value) and about 50 to the pound weight.
If you wish to use DnD rulebook prices simply convert them all to sp and then treat 1sp as 1 penny. Very cheap items will need to be bought in multiples until the price reaches (or rounds up to) a quarter, half or whole penny. Luxuries for the wealthy who aren’t counting their pennies might be marked up to the next shilling, noble, mark or pound.
Researching this post, I was slightly surprised to discover that my own country did not adopt the familiar copper penny until the 19th century. So this is actually pretty modern, but may feel right for a gunpowder-age, piratical or steampunk setting.
The units of account are the pound, shilling and penny, with 12 pence equalling 1 shilling and 240 pence or 20 shillings equalling 1 pound. Prices are higher in this system than in the medieval system, with a daily labourer’s wage about a shilling or two.
The pound coin is called a sovereign (which I shall use for the money unit from here to avoid confusion with the weight), and is of gold, weighing about 50 to the pound (nearer 57 historically but let’s use a round number). Private banks and the national bank also issue paper money, in amounts over one sovereign.
Everyday transactions are often in silver. The silver shilling (12 pence and 1/20 sovereign) weighs 80 to the pound. Other silver denominations may include 3 pence, 4 pence (groat), 6 pence (‘tanner’), 24 pence (florin), 30 pence (half crown), 48 pence (double florin) and 60 pence (crown). The coin weights are proportional to value so in play you can just keep track of the value of silver coinage carried and not worry too much about denominations.
Small change is in copper or bronze. The penny varied in weight but was always quite big—24 to the pound for a time, which works out at 10 pounds of bronze for a sovereign’s worth of currency. There are also half-penny and quarter-penny (farthing) coins in the same metal and of corresponding weights.
This is based on currencies of the Byzantine empire, the eastern Mediterranean survival of the Roman empire, which faded in power during the middle ages. You could use it if you want a slightly exotic feel compared to a western-Europe-style silver currency, and/or for a region where gold is relatively plentiful.
In this simplified version, the principal coin is the gold solidus, weighing about 100 to the pound (there were alternative names for similar coins under different coinage reforms, including the nomisma, histamenon and hyperpyron; in the west the coin was known as the bezant, for its origin).
Small change is provided by the bronze follis, of which 150 are worth 1 solidus and weigh 1 pound. At times smaller bronze coins were issued and in theory the smallest unit in the system is the nummus worth 1/40 follis and 1/6000 solidus, but at this size for the follis the smallest practical coin is probably the semi-follis.
Some emperors issued silver coins such as the miliaresion, which you may include weighing about the same as the follis and valued at 12 to the solidus. (If you want a gold-silver-bronze currency with simple ratios between all the coins you might adjust the follis to be worth 1/144 of a solidus so that it can be 1/12 of a miliaresion.)
The Byzantines were also fond of mixing metals. If you want to include an electrum coin (about ¼ gold and ¾ silver), you could have it weighing about as much as the solidus but with 1/3 the value. They also at times used billon, which is in general an alloy with a small amount of precious metal, but in Byzantine coinage tends to mean bronze with a silver coating. Coins in either of these metals could present a puzzle for those unfamiliar with them, because both more or less resemble silver (electrum at these proportions having only a pale yellow tinge and billon looking like silver on the surface but lacking weight for its size) but have different values.
This currency is based on that of Imperial Rome in its heyday.
A principal unit in this system is the sestertius, which at this time is a large coin of a gold-coloured type of brass called orichalcum. For a round number let us say it comes at 20 to the pound (it was actually larger still). It can be used in ones and twos, or in its half-sized version the dupondius, for modest purchases. It is also spoken of in up to hundreds or thousands as the denomination in which to express express larger sums (like the property, incomes or business deals of the wealthy, down to individual larger purchases like a mule).
Common purchases like daily groceries or tavern transactions are denominated in asses. The as is a copper coin, 40 to the pound like the dupondius, but worth only ¼ sestertius. You sometimes even see the semis (half an as) and the quadrans (quarter-as).
To make larger transactions of many sestertii practical, they could be conducted in silver. The main silver coin was the denarius, worth 4 sestertii or 16 asses and weighing about 100 to the pound (another round number; in reality the weight declined to over 130 to the pound). There was also the half-denarius called the quinarius.
The prestige and big-business coin is the aureus, a gold issue worth 100 sestertii and weighing about 50 to the pound (again this is a round number and in history the weight started at about 57 to the pound and declined as the demand for coin outstripped the supply of gold). You also get a half-aureus.
(I’ve updated this last section December 2020 to reflect the prices and denominations in the excellent book Pompeii: the Life of a Roman Town by Mary Beard.)
Do you find these coin system models useful? Have you got something like this in your game? Let us know in the comments.