How Exchange Rates Work: Mid-Market, Buy/Sell Spreads, and What Banks Don't Tell You

The Rate You See vs The Rate You Get

When you search “USD to EUR” on Google, you see a number — say, 0.91. This is the mid-market rate, the midpoint between what buyers are willing to pay and what sellers are asking for on global currency markets. It is the rate that banks trade among themselves, and it changes constantly throughout the trading day.

When you actually exchange money — at a bank, an airport kiosk, or through your credit card — you get a different number. The difference between what you get and the mid-market rate is the “spread,” and it represents the profit margin of whoever is doing the conversion. This spread is not always disclosed, and it varies enormously between providers.

The Mid-Market Rate Explained

The mid-market rate, also called the interbank rate or the spot rate, is determined by supply and demand on the foreign exchange market — the largest and most liquid financial market in the world, with over USD 7 trillion in daily trading volume. Currencies are traded in pairs (EUR/USD, GBP/JPY, AUD/USD), and the mid-market rate is the average of the buy and sell prices at any given moment.

This rate is important because it represents the “true” value of a currency at that instant, free from any retail markup. No consumer ever actually transacts at the mid-market rate — the spread is always present — but the gap between the mid-market rate and the rate you receive measures how much you are paying for the conversion.

The Buy/Sell Spread

Currency providers quote two rates: the buy rate and the sell rate. If you are a consumer buying euros with US dollars, the provider sells euros to you at the “sell” rate, which is higher than the mid-market rate. If you are selling euros back to the provider for US dollars, they buy euros from you at the “buy” rate, which is lower than the mid-market rate.

The difference between these two rates is the spread, and it is the provider’s revenue for facilitating the exchange. A narrow spread is good for consumers. A wide spread is good for the provider. Different providers charge dramatically different spreads for the same currency pair.

At an airport kiosk, the spread might be 7–14% — meaning you lose 7–14% of your money’s value compared to the mid-market rate. At a major bank branch, the spread is typically 3–5%. At a high street bureau, 3–6%. Through an online service like Wise, the spread can be 0.5–1.5%. Through a credit or debit card using the Visa or Mastercard network rate, 0.2–0.5%.

The most deceptive marketing practice in currency exchange is advertising “zero commission” or “no fees” while hiding a wide spread in the exchange rate itself. The consumer sees “no commission” and assumes they are getting a good deal, but the effective cost is built into the rate. Always compare the rate you are offered against the mid-market rate for a true cost comparison.

Fixed vs Floating Exchange Rates

Most major currencies float freely, meaning their value is determined by market forces minute by minute. The US dollar, euro, British pound, Japanese yen, Australian dollar, and Canadian dollar are all floating currencies. Their exchange rates move constantly in response to economic data, central bank policy, political events, and market sentiment.

Some countries peg their currency to another — the Hong Kong dollar is pegged to the US dollar within a narrow band, for example. The Saudi riyal and UAE dirham are also pegged to the US dollar. Pegged currencies have fixed or nearly fixed exchange rates that change only when the central bank adjusts the peg.

Other countries have managed floats, where the central bank intervenes periodically to keep the exchange rate within a desired range. The Chinese renminbi and Singapore dollar operate under managed float regimes.

For travellers, the distinction matters because pegged and managed currencies can diverge from their official rate if market pressure builds. Always check the current effective rate, not just the official peg, particularly for currencies in countries with economic or political instability.

How Banks and Card Networks Set Their Rates

Visa and Mastercard process the vast majority of international card transactions and each publishes a daily exchange rate used for settlements between banks. The Visa rate and Mastercard rate are both based on wholesale market rates with a small spread, typically 0.2–0.5%, which is the network’s fee for processing the currency conversion.

Your issuing bank may apply the network rate directly (which is the most consumer-friendly approach), or it may apply its own rate, which often includes an additional 2–4% spread. Some banks disclose which rate they use; many do not. If your card terms say “we use the exchange rate determined by Visa/Mastercard,” you are getting the network rate. If the terms say “we determine the exchange rate,” the bank is adding its own markup.

American Express operates its own payment network and uses its own exchange rates, which are generally slightly less favourable than Visa and Mastercard rates. The difference is small — typically 0.5–1% worse — but it exists. For travel to countries where Amex acceptance is limited anyway, this is an additional reason to carry a Visa or Mastercard.

Spot Rate vs Tourist Rate: The Airport Trap

The “tourist rate” is the informal term for the heavily marked-up exchange rates offered at airports, hotels, and tourist-oriented exchange booths. These rates can be 10–15% worse than the mid-market rate. The providers know their customers are captive — they need currency immediately, often have no alternatives nearby, and are unlikely to comparison shop while rushing to catch a taxi.

The physical presentation amplifies the effect. Airport kiosks display large “We Buy” and “We Sell” boards with rates that appear official and authoritative. The spread is not shown. The mid-market rate is not shown. The customer sees a number and accepts it as “the rate.” This combination of captive customers, absence of comparison, and authoritative presentation is why airport exchange remains profitable despite offering objectively terrible value.

How to Minimize the Spread

The most effective strategy is to use payment methods that apply the smallest spread. These are, in order of cost-effectiveness: a multi-currency account like Wise that uses the mid-market rate with a transparent fee; a credit or debit card that uses the Visa or Mastercard network rate; and a fee-refunding bank debit card for ATM withdrawals. All three approaches keep the total spread — explicit fees plus hidden rate margin — under 1–2%.

Avoiding the worst spreads is equally important. Never exchange currency at an airport unless the amount is trivially small. Never accept dynamic currency conversion at a payment terminal or ATM. Never exchange money at a hotel front desk, which typically offers rates 10–15% worse than a bank ATM.

When you do need physical currency, withdraw from a bank ATM at your destination using a card that rebates ATM fees or carries no foreign transaction fee. The ATM will dispense local currency, and your card network will convert at the wholesale rate. This approach typically yields a spread of 0.5–1% total, compared to 5–14% at an airport kiosk.

Real-World Cost Comparison

To make this concrete, suppose you need EUR 1,000 for an upcoming trip, and the mid-market rate is 1 USD = 0.91 EUR. At this rate, EUR 1,000 costs approximately USD 1,099.

At an airport kiosk with a 10% spread, you might pay USD 1,209. At a major bank with a 4% spread, USD 1,143. At a high street bureau with a 5% spread, USD 1,154. Using a Wise transfer with a 0.8% fee, USD 1,108. Using a fee-free card with the Visa network rate, approximately USD 1,104.

The difference between the airport kiosk and the fee-free card is USD 105 — on a single exchange of EUR 1,000. Scale this up to multiple exchanges over a lifetime of travel, and the cumulative cost of consistently choosing expensive exchange channels is thousands of dollars.

Bottom Line

The exchange rate you actually receive on a currency conversion is determined by who is doing the converting, not by the global currency markets. The mid-market rate is a reference point, not an achievable target, but the gap between the reference point and what you get reflects how much you are paying. Minimizing this gap is a straightforward exercise in choosing the right payment tools and avoiding the most expensive conversion channels.

Last updated: July 2026. Exchange rates referenced are illustrative and based on mid-2026 levels. Actual rates vary constantly. Currency markets, card network policies, and provider spreads change. Always check current rates before exchanging significant amounts. This does not constitute financial advice.