How Currency Exchange Rates Work (And Why They Change Daily)
Understand why currency exchange rates fluctuate daily, how banks set rates, and what factors drive USD, EUR, and other major pairs.
The global foreign exchange market, known as Forex, trades over 7.5 trillion US dollars every single day according to the Bank for International Settlements 2022 triennial survey. That makes it the largest and most liquid financial market on earth, operating 24 hours a day, five days a week across time zones from Sydney to London. Understanding why exchange rates move is essential for travelers, importers, exporters, and anyone holding foreign currency.
What Is an Exchange Rate?
An exchange rate is the price of one currency expressed in terms of another. When you see EUR/USD at 1.0850, it means one euro buys 1.0850 US dollars. Rates are quoted in pairs: a base currency and a quote currency. The rate you see on Google is the mid-market rate โ the midpoint between the buy and sell prices that banks and institutions trade at. Retail customers and tourists receive a spread on top, typically 1 to 5 percent wider.
- Mid-market rate: the fair interbank rate, no spread included
- Bid price: what the dealer will buy the base currency for
- Ask price: what the dealer will sell the base currency for
- Spread: the difference between bid and ask โ the dealer profit margin
Five Key Factors That Move Exchange Rates
Interest rate decisions by central banks are the single most powerful short-term driver of exchange rates. When the US Federal Reserve raised its benchmark rate from near zero to 5.25 to 5.50 percent between March 2022 and July 2023, the US Dollar Index (DXY) surged to a 20-year high above 114. Higher interest rates attract foreign capital seeking better returns, increasing demand for that currency.
Inflation, trade balances, political stability, and market speculation complete the five major drivers. A country with a current account surplus โ meaning it exports more than it imports โ sees rising demand for its currency. Japan, Germany, and China have historically maintained strong surpluses, which supports their currencies over the long term.
Fixed vs Floating Exchange Rate Systems
Not all currencies float freely. The United States, Eurozone, Japan, and the United Kingdom use floating rate systems where the market determines value. Countries like Saudi Arabia, the UAE, and Hong Kong peg their currencies to the US dollar at a fixed rate, requiring their central banks to hold large USD reserves and actively intervene to maintain the peg. China uses a managed float, setting a daily reference rate and allowing the yuan to move within a 2 percent band.
When traveling, avoid airport currency exchange booths โ they typically charge spreads of 8 to 12 percent above the mid-market rate. Use a no-foreign-transaction-fee credit card or withdraw from a local ATM for rates within 1 to 2 percent of mid-market.
How to Read a Currency Pair and Calculate Conversions
To convert 1,000 US dollars to euros when EUR/USD = 1.0850: divide 1,000 by 1.0850 to get 921.66 euros. To convert euros back to dollars, multiply 921.66 by 1.0850 to get 1,000 dollars. Always divide when converting from the quote currency and multiply when converting from the base currency. Cross rates (non-USD pairs) are calculated by dividing two USD-based rates.
- USD to EUR: divide USD amount by EUR/USD rate
- EUR to USD: multiply EUR amount by EUR/USD rate
- Cross rate GBP/JPY: divide GBP/USD by USD/JPY
- Best converter tools: Wise, XE.com, or Google Finance for live rates
Conclusion
Exchange rates reflect the collective judgment of millions of market participants about a country relative economic strength, inflation outlook, and political stability. Central bank interest rate decisions, particularly from the US Federal Reserve, the ECB, and the Bank of Japan, drive the largest short-term moves. For everyday conversions, always use the mid-market rate as your benchmark, and factor in the realistic spread you will pay before making financial decisions involving foreign currency.