Currency Exchange Margin Calculator
Find out how much extra you are really paying when a bank, exchange counter, or app offers you a currency rate below the actual market rate.
About this currency exchange margin calculator
Currency exchange services rarely give you the true market/interbank rate, they build in a margin, which can be hidden rather than charged as a visible fee. This calculator reveals exactly how much that margin is actually costing you.
How currency exchange margin calculator works
The formula is: Margin % = ((Market Rate − Offered Rate) ÷ Market Rate) × 100, and Extra Cost = Amount × |Market Rate − Offered Rate| ÷ Market Rate. For example, exchanging $1,000 at a rate 2% below market costs you roughly $20 more than the fair market exchange would.
Common uses
- Checking how much a bank or exchange counter is really marking up a currency exchange
- Comparing margins across different exchange services before a trip
- Understanding the true cost of an international money transfer
How to use this tool
- Enter the current market/interbank exchange rate.
- Enter the rate actually offered to you.
- Enter the amount you plan to exchange.
- See the margin percentage and extra cost.
What to know before using it
You need the actual current market/interbank rate for an accurate comparison, available from most financial data sites, the offered rate is whatever your bank, exchange counter, or app actually quotes you.
Privacy and browser-first processing
This tool runs entirely in your browser using JavaScript. Nothing you enter is uploaded or stored.
Frequently asked questions
Where do I find the real market exchange rate?
Most financial news sites and currency converter tools publish the current mid-market (interbank) rate, which is the benchmark this calculator compares against.
Is a 2-3% margin normal?
Margins vary widely by provider, traditional banks often charge more, while some specialized currency services charge less, comparing a few options before a large exchange is usually worth the few minutes it takes.