As we begin discussing exchange rates, we must make the same distinction that we made when discussing GDP. Namely, how do nominal exchange rates and real exchange rates differ?
The nominal exchange rate is the rate at which currency can be exchanged. If the nominal exchange rate between the dollar and the lira is 1600, then one dollar will purchase 1600 lira. Exchange rates are always represented in terms of the amount of foreign currency that can be purchased for one unit of domestic currency. Thus, we determine the nominal exchange rate by identifying the amount of foreign currency that can be purchased for one unit of domestic currency.
The real exchange rate is a bit more complicated than the nominal exchange rate. While the nominal exchange rate tells how much foreign currency can be exchanged for a unit of domestic currency, the real exchange rate tells how much the goods and services in the domestic country can be exchanged for the goods and services in a foreign country. The real exchange rate is represented by the following equation: real exchange rate = (nominal exchange rate X domestic price) / (foreign price).
Let's say that we want to determine the real exchange rate for wine between the US and Italy. We know that the nominal exchange rate between these countries is 1600 lira per dollar. We also know that the price of wine in Italy is 3000 lira and the price of wine in the US is $6. Remember that we are attempting to compare equivalent types of wine in this example. In this case, we begin with the equation for the real exchange rate of real exchange rate = (nominal exchange rate X domestic price) / (foreign price). Substituting in the numbers from above gives real exchange rate = (1600 X $6) / 3000 lira = 3.2 bottles of Italian wine per bottle of American wine.
By using both the nominal exchange rate and the real exchange rate, we can deduce important information about the relative cost of living in two countries. While a high nominal exchange rate may create the false impression that a unit of domestic currency will be able to purchase many foreign goods, in reality, only a high real exchange rate justifies this assumption.
An important relationship exists between net exports and the real exchange rate within a country. When the real exchange rate is high, the relative price of goods at home is higher than the relative price of goods abroad. In this case, import is likely because foreign goods are cheaper, in real terms, than domestic goods. Thus, when the real exchange rate is high, net exports decrease as imports rise. Alternatively, when the real exchange rate is low, net exports increase as exports rise. This relationship helps to show the effects of changes in the real exchange rate.