Currency Conversion

Currency conversion is the process of turning an amount of money in one currency into an equivalent amount in another, using an exchange rate. It happens whenever a traveller pays abroad, a shopper buys from a foreign website, a business pays an overseas supplier or an investor buys foreign assets. The conversion may be carried out by a bank, a card network, a payment provider, a money transfer business or a dealer in the foreign exchange market.

In payments, the main questions are who performs the conversion, at what rate and with what charges. The rate used can be close to the mid-market rate or include a margin, known as a currency conversion markup. Separate fees may also apply. The total cost of conversion is the difference between what the customer pays and what they would have paid at the mid-market rate.

A conversion multiplies the amount by the applicable rate:

The rate is quoted as the number of units of the quote currency for one unit of the base currency. If the rate for euros into US dollars is 1.10, then 500 euros converts to $500 \times 1.10 = 550$ US dollars. If the provider instead uses 1.078, which includes a 2% margin, the customer receives $500 \times 1.078 = 539$ dollars, and the cost of conversion is 11 dollars before any separate fee.

Card payments. When a card is used in a foreign currency, the card network usually converts the amount into the cardholder's billing currency at its daily rate, and the issuer may add a foreign transaction fee. Alternatively, the merchant's provider may offer dynamic currency conversion at the till or checkout, converting the price into the cardholder's currency at its own rate, which is often less favourable.

Bank and wire transfers. The sending bank, the receiving bank or an intermediary may convert. If the sender pays in its own currency, the receiving side converts; if the sender pays in the recipient's currency, the sending bank converts. Unclear instructions can lead to double currency conversion, where an amount is converted twice.

Money transfer services. Remittance and fintech providers quote a rate and fee before the customer pays, often converting at or near wholesale rates and earning revenue from a margin or a fee.

Business FX. Companies convert through banks, FX brokers or multi-currency platforms, using spot transactions for immediate needs and forward contracts to fix rates for future payments.

Conversion costs come from three sources: the margin built into the rate, explicit fees and any spread between the buy and sell rate when converting back. Regulators increasingly require providers to show these clearly. In the European Union, card issuers and providers offering currency conversion must express the total conversion charge as a percentage mark-up over the latest euro foreign exchange reference rates published by the European Central Bank, so consumers can compare offers. In the United States, providers of remittance transfers must disclose the exchange rate and the amount the recipient will receive before payment.

Conversion exposes parties to exchange rate movements between the time a price is set and the time money moves. A merchant pricing in one currency but paid in another faces currency exposure, as does a traveller whose card transaction is converted days later at a different rate. Businesses manage this through hedging, local currency accounts and pricing strategies. Refunds on card payments can return a different amount from the original charge if rates have changed in between.

In some countries currency conversion is restricted. Governments may limit who can buy foreign currency, require approval for conversions above certain amounts or set an official exchange rate that differs from the market rate. Such controls can create parallel markets and complicate cross-border payments, and international businesses must take them into account when planning how and where to convert funds.

For individuals, paying in the local currency and letting the card network convert is usually cheaper than accepting dynamic currency conversion. Comparing the quoted rate against the mid-market rate reveals the margin. For businesses, consolidating conversions, holding balances in frequently used currencies and negotiating rates based on volume can significantly reduce costs over a year.