The exchange rate that is quoted and used for a FX transaction involving two specific currencies (a currency pair), where both are valued against a third currency. In the foreign exchange (FX) markets, a reserve currency is usually used to establish the values of the pair of currencies being exchanged. It is a cross rate involves the rate relating to any exchange of two currencies that are not the official currency in the country in which the quote is issued.

For example, any FX exchange of two currencies that are both valued against the U.S. dollar is considered to involve a cross rate.