How exchange rates work and when to lock in a rate

Exchange rates determine how much your money is worth in another country. Whether you are traveling abroad, running a freelance business with international clients, or sending money to family overseas, understanding how rates work saves you real money. The difference between a fair rate and a bad one can cost you 5-10% on every transaction.

What determines exchange rates

Exchange rates move constantly based on supply and demand. When more people want to buy a currency, its value goes up. When more people want to sell, it goes down. Behind these simple mechanics are complex factors.

Interest rates set by central banks are the biggest driver. Higher interest rates attract foreign investors looking for better returns, which increases demand for that currency. The US Federal Reserve, European Central Bank, and Bank of Japan all influence global currency markets with their rate decisions.

Inflation also plays a major role. Countries with low inflation tend to have stronger currencies because their purchasing power holds steady. High inflation erodes currency value, making imports more expensive and reducing the standard of living.

Economic stability matters too. Countries with stable governments, strong legal systems, and consistent economic growth attract investment, which supports their currency. Political turmoil, corruption, or default risk all weaken a currency.

The spread: where you lose money

Every currency transaction involves two rates: the buy rate and the sell rate. The difference between them is the spread. That is how banks and exchange services make money.

If the interbank rate (the real market rate) is 1.10 USD per EUR, a bank might offer you 1.07 to buy euros and charge you 1.13 to sell them back. That 6-cent spread is roughly 5.5% of your transaction. On a $5,000 transfer, that is $275 in hidden costs.

Always compare the rate you are offered to the mid-market rate you see on Google or XE. Any service that charges more than 1-2% above the mid-market rate is expensive. Many airport exchange kiosks charge 8-12% spreads. Avoid them.

When to lock in a rate

Locking in an exchange rate means agreeing to a fixed rate for a future transaction. This is called a forward contract. Businesses use forward contracts to protect their profit margins from currency fluctuations.

If you are a freelancer paid in USD but your expenses are in EUR, a sudden drop in the dollar could wipe out your profit on a project. Locking in a rate guarantees that you know exactly how much you will receive in your local currency.

For personal travel, forward contracts are usually not practical — they are designed for larger amounts. But you can lock in a rate when buying travel money online from specialist services. Some let you order currency at a fixed rate and pick it up later.

Dynamic currency conversion: the hidden trap

When you pay with a credit card abroad, the merchant may offer to charge you in your home currency instead of the local currency. This is called dynamic currency conversion. Always decline it.

The exchange rate offered by the merchant is almost always worse than what your bank would give you. You pay 3-7% more for the convenience of seeing the price in your own currency. Always choose to pay in the local currency and let your bank handle the conversion at their standard rate.

Using the currency converter

The Currency Converter gives you real-time mid-market rates for any currency pair. Use it as your reference point when evaluating any exchange offer. If you are getting a rate more than 2% away from the mid-market rate, you are being overcharged.

For frequent international transactions, consider a multi-currency account from services like Wise or Revolut. These hold multiple currencies and let you convert at near-market rates whenever you choose. You can watch rates and convert when the rate is favorable rather than being forced to convert at the point of sale.

Practical tips

Check rates before you travel to establish a baseline. Use fee-free debit cards for ATM withdrawals abroad. Avoid exchanging money at airports, hotels, and tourist areas where spreads are widest. Send larger amounts less frequently to minimize fixed transfer fees. And always read the fine print on exchange rate guarantees — some come with conditions that make them less valuable than they appear.

Understanding exchange rates is not complicated once you know what to look for. The mid-market rate is your truth. Everything else is a cost.