Exchange rate

An exchange rate states the relative value of two currencies by identifying a base currency and a quote currency. In the quotation 1.2500 USD/EUR, the euro is the base currency and one euro costs 1.25 U.S. dollars. The same relationship can be written as 0.8000 EUR/USD, so changing the quotation convention changes the number but not the underlying value.

Rates may be quoted as spot rates, for exchange near the present date, or as forward rates, agreed today for settlement on a later date. A currency can appreciate when it buys more of another currency and depreciate when it buys less. Financial institutions commonly quote bid and ask prices; the difference, called the spread, compensates dealers for intermediation and risk. Exchange-rate notation and terminology vary by market, so the currency pair must always be read explicitly.¹

Market exchange rates are formed primarily by purchases and sales of currencies in the foreign-exchange market. Banks, corporations, investment funds, governments, and other participants trade to settle invoices, hedge exposures, invest, borrow, or speculate. Interest-rate expectations, inflation prospects, economic growth, fiscal conditions, political risk, and global demand for safe assets can all shift supply and demand.

Central banks influence rates through monetary policy, foreign-exchange intervention, capital regulations, and communication, although their ability to control a freely floating currency is limited. Exchange-rate regimes range from independent floating to fixed or tightly managed arrangements. A country may also peg its currency to another currency or to a basket, requiring reserves and policy measures to defend the target. The Bank for International Settlements describes foreign exchange as the world’s largest financial market, with trading distributed across major international centers.²

Exchange rates transmit changes in international prices into domestic economies. A depreciation usually makes a country’s exports cheaper for foreign buyers and its imports more expensive in domestic currency, while an appreciation tends to have the opposite effects. The eventual trade response depends on contracts, production capacity, and the price sensitivity of buyers; trade balances may initially worsen after a depreciation before improving, a pattern known as the J-curve effect.

Currency movements also affect inflation, especially where imported energy, food, machinery, or intermediate goods are important. Borrowers with foreign-currency debt can face sharply higher repayment costs after a depreciation, even if their revenues are domestic. Conversely, exporters earning foreign currency may gain, while households and firms with foreign assets may see their domestic-currency values change. These distributional effects mean that no single exchange rate is uniformly beneficial to every sector.³⁴

Exchange rates can differ from their long-run purchasing-power relationships because identical goods are not perfectly tradable and services, taxes, transport costs, and market barriers vary across countries. Purchasing power parity is therefore a useful analytical benchmark rather than a rule that daily market rates must obey. Economists also distinguish nominal rates from real exchange rates, which adjust for relative price levels and better indicate the international competitiveness of goods and services.

Many countries publish official or reference rates that are calculated from market observations, but these are not necessarily prices at which every person can transact. Retail customers generally receive less favorable rates because of spreads, commissions, and payment-network charges. A further complication is the existence of multiple rates in countries with capital controls or currency shortages. In such cases, an official rate, a regulated rate, and a parallel-market rate may coexist, creating incentives for arbitrage and complicating economic statistics.¹⁵

Base currency

The first currency in a currency pair; it is the unit whose price is being stated.

Quote currency

The second currency in a currency pair; it expresses the price of one unit of the base currency.

Spot rate

The exchange rate for a currency transaction settled under ordinary near-term market conventions.

Forward rate

A rate agreed for exchanging currencies on a specified future date.

Real exchange rate

A nominal exchange rate adjusted for relative price levels between economies.

Purchasing power parity

The proposition that exchange rates tend toward levels that equalize the prices of comparable goods across countries, after appropriate adjustments.