# How can the value of older currencies be expressed in modern units? How is the conversion rate calculated? [duplicate]

We can pretty often read something like.. "He owned this sum of silver/gold which is equal to this sum of dollars in our time."

But how is this calculated? How can you know what a 1000 dollars was in Roman Empire for example? By comparing prices for some goods? But is it an adequate method?

• We actually only really read such statements in more recent writings, such as the last couple of centuries or so, when inflation are (more or less) tracked. Conversion can easily be made by adjusting for inflation. Anything further back though cannot really be converted as such. In your example of Ancient.Roman, few if any serious writer would express gold or silver as "equal to x modern dollars". The best anyone would do for ancient price numbers is to try contextualise it by providing the average income of people at the time. Dec 21, 2015 at 9:24
• Because ancient currencies were specie currencies one can usually get in the right ballpark simply by equating the ancient value of the precious metal content to modern commodity prices. There are additional variables at work, but they are usually secondary effects. Dec 21, 2015 at 9:36
• How much did it cost a citizen to buy a hamburger? Dec 21, 2015 at 14:08
• yeah, this is something i was pretty curious about too Dec 21, 2015 at 14:45
• The department in charge of the Consumer Price Index throws math at the problem. The calculations to determine the basket of goods and of changes in the basket of goods is recondite; fortunately the only thing that matters is that it is transparent - that everyone can do the calculations and use them as rough guides to price equivalency.
– MCW
Dec 21, 2015 at 15:49