The value of money is determined by the demand for it, just like the value of goods and services. There are three ways to measure the value of the dollar. The first is how much the dollar will buy in foreign currencies. That’s what the exchange rate measures. Forex traders on the foreign exchange market determine exchange rates. They take into account supply and demand, and then factor in their expectations for the future. For this reason, the value of money fluctuates throughout the trading day. The second method is the value of Treasury notes. They can be converted easily into dollars through the secondary market for Treasurys.