Currency Conversion: A Practical Guide for Travelers and Professionals
Currency conversion affects nearly everyone in the modern world — from international travelers exchanging money at the airport, to businesses invoicing foreign clients, to investors tracking global asset values, to online shoppers purchasing from international retailers. Understanding how currency markets work helps you make smarter decisions about when and how to exchange money.
How Exchange Rates Work
Currency exchange rates represent the price of one currency expressed in terms of another. They fluctuate constantly during trading hours (24 hours a day, 5 days a week) based on supply and demand dynamics driven by international trade flows, capital investment movements, government policy decisions, inflation rates, interest rate differentials, and market speculation.
The world's most actively traded currencies — the US Dollar (USD), Euro (EUR), Japanese Yen (JPY), British Pound (GBP), and Swiss Franc (CHF) — collectively make up the bulk of global forex trading volume. The USD serves as the world's primary reserve currency, meaning most international trade and financial transactions are priced in USD even when neither party to the transaction is American.
Bid-Ask Spread: What Banks and Exchange Bureaus Charge
When you exchange currency at a bank or bureau de change, you'll notice two rates: the "buy" rate (what they'll pay you for foreign currency) and the "sell" rate (what they'll charge you for foreign currency). The difference between these rates is the bid-ask spread — the profit margin for the currency exchanger.
Airport exchange bureaus notoriously charge the widest spreads, sometimes 10–15% worse than the mid-market rate. Banks offer better rates to account holders. Dedicated online forex services typically come closest to the interbank mid-market rate. Our tool shows the interbank mid-rate (the fair market midpoint) as an indicative reference.
Tips for Getting the Best Exchange Rates
- Avoid airport kiosks: Convenience comes at a significant markup. Exchange what you need before traveling.
- Use ATMs abroad: Withdrawing from a local ATM in the destination country typically gives better rates than pre-exchanging, though ATM fees vary.
- Zero-markup travel cards: Cards from companies like Wise (formerly TransferWise), Revolut, or Charles Schwab travel debit offer near-midmarket rates with minimal fees.
- Monitor rate trends: For large conversions, monitoring rates over several days or weeks can help you time the exchange advantageously.