Currency Converter

How Does a Currency Converter Work?

A currency converter calculates the equivalent value of an amount in a source currency relative to a target currency by multiplying the amount by the corresponding exchange rate. The exchange rate is the price at which one currency exchanges for another in international financial markets. For example, if the EUR/USD exchange rate is 1.09, one euro equals 1.09 US dollars. To convert in the reverse direction, divide instead of multiply: 1 dollar equals 1/1.09 = 0.917 euros.

Exchange rates fluctuate constantly due to macroeconomic factors including interest rate differentials between countries, trade balances, inflation, political stability, and market sentiment. The most traded currencies in the world are the US dollar (USD), euro (EUR), Japanese yen (JPY), British pound sterling (GBP), and Swiss franc (CHF), which together account for the majority of daily trading volume in the forex market — the largest financial market in the world with over $7 trillion traded daily.

Interbank vs. Retail Exchange Rates

Different exchange rates apply depending on who is making the transaction. The interbank rate — also called the market rate or spot rate — is the price at which large banks exchange currencies with each other. It is the most favorable rate and serves as the reference that online conversion tools display.

The rate your bank, exchange bureau, or international payments platform offers always includes a margin (spread) above the interbank rate, which is their profit for the service. This margin can range from 0.5% on specialized platforms like Wise or Revolut to 3–5% at traditional banks or airports. For international transfers or purchases abroad, comparing the real exchange rate including all costs is essential for minimizing conversion costs.

Tips for Saving on Currency Conversions

To minimize costs when converting currencies: use specialized international payment platforms (Wise, Revolut) that offer rates close to the interbank rate with fixed, transparent fees rather than traditional banks with high margins. Avoid exchanging money at airports or hotels, where margins are typically highest. For international travel, a debit card with no foreign transaction fees allows paying directly in local currency at the market rate without surcharge.

Frequently Asked Questions

Are the exchange rates shown accurate for bank transactions?

The rates shown are reference market rates (interbank rates). Banks and payment platforms apply their own margin above this rate, so the actual rate of your transaction will be slightly less favorable. The difference between the reference rate and the applied transaction rate is the real cost of conversion.

How often do exchange rates change?

Exchange rates fluctuate continuously during global financial market hours (24 hours a day, Monday to Friday). For most everyday purposes, rates vary between 0.1% and 1% during a normal trading day. During periods of high volatility — financial crises, elections, major economic data releases — variations can be larger.

What is a cross rate?

A cross rate is the exchange rate between two currencies that do not include the US dollar as a base currency, calculated from their respective rates against the dollar. For example, the EUR/GBP rate is derived from EUR/USD and GBP/USD. Most currency converters calculate these cross rates automatically.