Currency rates are determined the current price of the currency in a open market auction of the currency. This process of determining the currency rate is called forex trading. A currency rate of exchange is constantly changing because economic factors effect the amount for which investors are willing to buy or sell their currency. This calculator is updated to a recent currency rate as reported currency markets. Banks use a recent currency rate exchange to determine how much to charge somebody off the street for their foreign currency. You may select currencies below to determine the current currency rate.