Exchange Rate Definition: An exchange rate is the price of one currency expressed in units of another, such as 1.10 US dollars per euro or 150 yen per dollar. Most major currencies float, so their rate is set continuously by supply and demand in the forex market, while pegged currencies are held at or near a fixed level by their central bank.
What Is an Exchange Rate?
Every cross-border purchase needs a conversion. A German car sold in the US, a US bond bought by a Japanese pension fund, a hotel room booked in Bangkok: each one requires someone to swap one currency for another. The exchange rate is the price of that swap.
Rates are written as pairs. EUR/USD at 1.1000 means one euro costs 1.10 dollars, and the same rate seen from the other side is about 0.91 euros per dollar. The currency on the left is the base, fixed at one unit, and the one on the right is the quote currency that expresses its price.
For most of the 20th century, major rates were fixed by governments. That changed on 15 August 1971, when President Nixon ended the dollar’s convertibility into gold and broke the Bretton Woods system. By 1973 the major currencies were floating, and exchange rates became market prices that move every second the market is open.
How Are Exchange Rates Determined?
With that background, the mechanics are easier to follow. A floating exchange rate is set the same way as the price of any traded asset: by the balance of buyers and sellers. What makes currencies special is who those buyers and sellers are and why they need the money.
Interest rates are the strongest short-term driver. If the Fed raises rates while the ECB holds, dollar deposits and bonds pay more, investors sell euros to buy dollars, and EUR/USD falls. Inflation works over longer horizons: a currency that loses purchasing power at home tends to lose value abroad too. Trade and capital flows add steady demand, as exporters convert foreign earnings back home and foreign investors buy local stocks and bonds.
Policy can overwhelm all three. On 22 September 1985, the finance ministers of the US, Japan, West Germany, France and the UK signed the Plaza Accord, agreeing to push the dollar lower through coordinated selling. USD/JPY fell from about 240 to about 150 within a year. No change in trade balances could have moved the yen that far that fast; five governments deciding to sell dollars did.
For a business, even a smaller move changes the bill. A US importer owing €1 million pays $1.1 million at 1.1000, but $1.2 million if EUR/USD climbs to 1.2000 before the invoice is due. That $100,000 difference comes purely from the exchange rate, which is why companies use hedging tools such as forward contracts to fix the rate in advance.
Types of Exchange Rate Regimes
- Free float: the market sets the rate and the central bank rarely intervenes. The US dollar, euro, yen, pound and Australian dollar all float.
- Managed float: the rate moves with the market, but the central bank steps in to slow sharp moves. China’s yuan trades within a band around a daily reference rate set by the People’s Bank of China.
- Fixed or pegged: the central bank holds the rate at a set level against another currency, backed by its foreign reserves. The Hong Kong dollar has been tied to the US dollar since 1983, and the Saudi riyal since 1986.
Nominal vs. Real Exchange Rate
The rate on your screen is the nominal exchange rate: how many units of one currency buy one unit of another. It says nothing about what that money can actually buy in each country.
A real exchange rate adjusts the nominal rate for the price levels in both economies. Suppose USD/TRY doubles over a year, but Turkish prices also double while US prices hold steady. In nominal terms the lira has halved, yet in real terms a Turkish exporter’s goods cost foreign buyers about the same as before. Economists and central banks watch the real rate because it measures competitiveness, while traders mostly trade the nominal one.
Why Is the Exchange Rate Important for Traders?
An exchange rate compresses a whole relationship between two economies into one number. Every rate decision, inflation print and election outcome eventually shows up in it, which is why forex traders spend more time reading central bank statements than company reports.
That also makes rates hard to forecast. Several drivers pull at once, and a rate hike can strengthen a currency one month and weaken it the next if markets decide it will cause a recession. Even long-run anchors like purchasing power parity can leave a currency over- or undervalued for years.
Pegs carry a different risk. A fixed rate looks stable only as long as the central bank has the reserves and the political will to defend it. When a peg breaks, the rate usually jumps in one gap, and traders on the wrong side cannot exit at any price in between.
Key Takeaways
- An exchange rate is the price of one currency in terms of another, shown as a pair with the base currency fixed at one unit.
- Floating rates are set by supply and demand, driven mainly by interest rate gaps, inflation and trade and capital flows.
- Coordinated government action, as in the 1985 Plaza Accord, can move rates further and faster than economic data.
- Regimes range from free floats to managed floats to hard pegs, and each carries a different kind of risk.
- The nominal rate is what you trade, while the real rate adjusts for inflation and shows whether a currency is actually cheap or expensive.
Who sets exchange rates?
For floating currencies such as the dollar, euro and yen, nobody sets them directly; the rate is the price at which banks, companies and investors are willing to trade at that moment. Central banks set or defend the rate only under pegs and managed floats.
Why is the exchange rate at my bank different from the one on the news?
The rate in the news is usually the interbank mid-market rate, halfway between the bid and the ask. Banks and card providers add a markup to that rate, which is how they earn on currency conversion.
Does a strong currency mean a strong economy?
Not necessarily. A currency can rise because of high interest rates or safe-haven demand during a crisis, and a weak currency can help an export-driven economy by making its goods cheaper abroad.
How often do exchange rates change?
Floating rates change many times per second while the forex market is open, which is 24 hours a day from Monday morning in Asia to Friday evening in New York.
