Exchange rates are one of the most important concepts in international economics because they show how currencies and goods connect across countries. When people travel, import products, export services, or invest abroad, exchange rates help determine how much one country’s money is worth compared with another’s. Therefore, understanding exchange rates helps explain trade, prices, inflation, and economic policy in an open economy.
What Are Exchange Rates?
An exchange rate is the price at which one country’s currency trades for another country’s currency. For example, when the exchange rate is expressed as yen per U.S. dollar, it tells us how many yen one dollar can buy.
However, exchange rates are not only about money. They also affect how expensive foreign goods look to domestic buyers and how attractive domestic goods look to foreign buyers. As a result, exchange rates influence imports, exports, and the trade balance.
Nominal Exchange Rate
The nominal exchange rate is the relative price of two currencies. In simple terms, it tells you how much foreign currency you can get for one unit of domestic currency.
For example, suppose one U.S. dollar buys 120 Japanese yen. In this case, the nominal exchange rate is 120 yen per dollar. An American who wants yen can exchange one dollar for 120 yen. Meanwhile, a Japanese buyer who wants dollars must pay 120 yen to get one dollar.
Currency Appreciation
A currency appreciates when it becomes more valuable compared with another currency. For instance, if the dollar goes from buying 120 yen to 130 yen, the dollar has appreciated because one dollar now buys more yen.
Consequently, foreign goods become cheaper for Americans. However, U.S. goods become more expensive for foreign buyers.
Currency Depreciation
A currency depreciates when it becomes less valuable compared with another currency. For example, if the dollar goes from buying 120 yen to 110 yen, the dollar has depreciated because one dollar now buys fewer yen.
Therefore, foreign goods become more expensive for Americans. At the same time, U.S. goods become cheaper for foreign buyers.
Real Exchange Rate
The real exchange rate compares the price of goods between two countries. While the nominal exchange rate compares currencies, the real exchange rate compares purchasing power across countries.
In other words, the real exchange rate tells us how many foreign goods can be exchanged for domestic goods.
Real Exchange Rate Formula
A simple formula is:
Real Exchange Rate = Nominal Exchange Rate × Domestic Price Level / Foreign Price Level
This formula shows that the real exchange rate depends on three things: the nominal exchange rate, domestic prices, and foreign prices.
For example, if domestic goods become more expensive compared with foreign goods, the real exchange rate rises. As a result, foreign buyers may purchase fewer domestic goods, and domestic buyers may choose more imports.
Nominal vs Real Exchange Rate
The difference between nominal and real exchange rates is important.
The nominal exchange rate focuses on currencies. It answers the question: “How much foreign money can one unit of domestic money buy?”
The real exchange rate focuses on goods. It answers the question: “How expensive are domestic goods compared with foreign goods?”
Therefore, the real exchange rate gives a better picture of international competitiveness. If domestic goods are relatively cheap, exports tend to rise. However, if domestic goods are relatively expensive, exports tend to fall.
Exchange Rates and the Trade Balance
The trade balance measures the difference between exports and imports. When exports are greater than imports, a country has a trade surplus. When imports are greater than exports, a country has a trade deficit.
Exchange rates affect the trade balance because they change the relative price of domestic and foreign goods.
When the Real Exchange Rate Is Low
When the real exchange rate is low, domestic goods are relatively cheap compared with foreign goods. Therefore, domestic consumers buy fewer imports, and foreigners buy more domestic goods.
As a result, net exports increase.
When the Real Exchange Rate Is High
When the real exchange rate is high, domestic goods are relatively expensive compared with foreign goods. Consequently, domestic consumers buy more imports, and foreigners buy fewer domestic goods.
Because of this, net exports decrease.
How the Real Exchange Rate Is Determined
In an open economy, the real exchange rate is determined by the relationship between net exports and net capital outflow.
Net exports represent the demand for domestic goods by foreign buyers. Meanwhile, net capital outflow reflects the supply of domestic currency used to purchase foreign assets.
The equilibrium real exchange rate occurs where the quantity of currency supplied for foreign investment equals the quantity of currency demanded for net exports.
How Fiscal Policy Affects Exchange Rates
Fiscal policy can influence exchange rates because it changes national saving, investment, and capital flows.
Expansionary Fiscal Policy at Home
Expansionary fiscal policy includes higher government spending or lower taxes. These policies can reduce national saving.
When national saving falls, the supply of funds available for foreign investment also falls. Therefore, the real exchange rate rises.
As the domestic currency becomes stronger, domestic goods become more expensive for foreign buyers. Consequently, exports fall, imports rise, and net exports decline.
Expansionary Fiscal Policy Abroad
Expansionary fiscal policy in foreign countries can raise the world interest rate. As a result, domestic investment may fall because borrowing becomes more expensive.
When domestic investment falls, more saving is available for foreign investment. Therefore, net capital outflow rises, the real exchange rate falls, and domestic goods become cheaper relative to foreign goods.
Consequently, net exports increase.
Investment Demand and Exchange Rates
A rise in investment demand can also affect exchange rates. For example, if a country introduces an investment tax credit, firms may want to invest more.
Because investment increases, less saving remains available for foreign investment. Therefore, the supply of domestic currency in foreign exchange markets falls.
As a result, the real exchange rate rises. The domestic currency appreciates, domestic goods become more expensive, and net exports fall.
Trade Policies and Exchange Rates
Trade policies are rules that affect imports and exports. Common examples include tariffs, quotas, and import restrictions.
At first, many people think tariffs reduce trade deficits by lowering imports. However, the effect is more complex.
A tariff may reduce imports directly. However, it can also raise the real exchange rate. When the real exchange rate rises, domestic goods become more expensive for foreign buyers. Consequently, exports may fall.
Therefore, protectionist trade policies may reduce the total amount of trade without improving the overall trade balance. They can help some domestic producers, but they may also reduce the gains from international trade.
Inflation and Nominal Exchange Rates
Inflation also affects exchange rates over time. When a country has higher inflation than another country, its currency usually loses purchasing power.
For example, if prices rise faster in the United States than in Japan, the dollar may buy fewer goods over time. Therefore, the nominal exchange rate adjusts to reflect the difference in inflation rates.
A simple way to understand this relationship is:
Change in Nominal Exchange Rate = Change in Real Exchange Rate + Difference in Inflation Rates
In general, countries with high inflation tend to experience currency depreciation. Meanwhile, countries with low inflation tend to have stronger currencies over time.
Why Exchange Rates Matter
Exchange rates matter because they affect everyday decisions and national economic outcomes. They influence travel costs, imported products, export competitiveness, investment returns, and inflation.
For businesses, exchange rates affect pricing and profits. For consumers, they affect the cost of imported goods. For governments, they influence trade policy, monetary policy, and fiscal policy.
Therefore, exchange rates are not just financial numbers. They are signals that connect domestic economic conditions with the global economy.
Conclusion
Exchange rates explain how currencies, prices, trade, and policy interact in an open economy. The nominal exchange rate shows the price of one currency in terms of another, while the real exchange rate shows the relative price of goods across countries.
When the real exchange rate rises, domestic goods become more expensive, and net exports usually fall. However, when the real exchange rate falls, domestic goods become more competitive, and net exports usually rise.
Ultimately, exchange rates help explain why countries trade, how policies affect international markets, and why inflation changes the value of money over time.
