Currency Exchange Calculator

Currency exchange converts one currency to another using the prevailing exchange rate, minus any fees or spread charged by the conversion provider. Getting the best rate requires understanding how rates are quoted and what hidden fees look like.

Basic conversion formula: Amount in Target Currency = Amount in Source Currency × Exchange Rate

Inverse rate: If USD/EUR = 0.92 (1 USD buys 0.92 EUR), then EUR/USD = 1 ÷ 0.92 = 1.087 (1 EUR buys 1.087 USD)

Reading a two-way quote. A bureau’s board shows two numbers for every currency, and they are quoted from the dealer’s point of view, not yours. If EUR shows 1.08 / 1.12, the dealer will buy euros from you at 1.08 and sell euros to you at 1.12. Both numbers are in your home currency per euro.

That means the higher number is the one that costs you money, which is the opposite of the instinct most people bring to it. Buying 1,000 euros costs 1,000 × 1.12 = 1,120 home. Selling 1,000 euros back gets you 1,000 × 1.08 = 1,080. Do both and you are down 40 without the market having moved a fraction.

The midpoint of those two numbers, 1.10 here, is the mid-market rate, and it is what the currency is actually worth. You never get it. Each direction costs you roughly half the spread, and a round trip costs you all of it.

Effective Rate = Mid-Market Rate × (1 − Spread%)

Spread benchmarks by provider:

• Airport currency exchange kiosks: 7–15% spread (worst option)
• Bank branch: 3–8% spread
• Credit card foreign transaction: 1–3% (listed as “foreign transaction fee”)
• ATM abroad (using home debit card): 1–3% + ATM operator fee $3–$7
• Wise (TransferWise): 0.4–1.5% spread (excellent)
• Revolut / N26 (during market hours): near 0% spread, 0.5–2% on weekends

Total cost of exchange: Total Fee (%) = Spread% + Fixed Fee ÷ Amount Converted × 100

Fixed fee impact: A $5 fixed fee on a $50 exchange = 10% effective fee. On a $500 exchange = 1% effective fee. Always convert larger amounts at once when using fixed-fee services.

Dynamic Currency Conversion (DCC), which you should always decline: When abroad, merchants offer to charge your card in your home currency “for convenience.” This locks in an unfavorable rate (typically 5–8% worse). Always choose to pay in the local currency and let your card handle the conversion.

Worked example: Converting $1,000 USD to euros for travel. Mid-market rate: 1 USD = 0.9200 EUR, so at the true rate your $1,000 is worth 920.00 EUR. Every figure below is in euros, measured against that 920.

Wise against the airport kiosk is a difference of 104.88 EUR, which at this rate is about $114. That is a hotel night in most of Europe, and the only work involved was opening an app before you left home instead of a booth after you landed.

Notice what is not in that table: a fee. None of these providers charged one. The entire difference is the rate, which is exactly why comparing advertised fees tells you almost nothing.