Exchange Rates Explained: Why Your Bank's Rate Is Different
By Ali Hamza · Published · 5 min read
On this page
- The four numbers behind any conversion
- A worked example
- Dynamic currency conversion: say "local currency"
- How to compare providers properly
- When a rough estimate is enough
- Invoicing in another currency
- Card, transfer or cash: how the costs differ
- Why the rate keeps changing
- Checklist before paying abroad
- Frequently asked questions
Your bank's exchange rate is different from the one you see online because the online figure is usually the mid-market rate, the midpoint between what currency traders buy and sell at, while banks and card providers add a margin (a worse rate) and sometimes a fee on top. Together these typically cost somewhere between under 1% and 5% or more of the amount, depending on the provider and how you pay. Calculators, including ToolMany's Currency Converter, are for estimates; always check the rate your provider will actually use.
A note about our own converter: it uses a small table of fixed reference rates for six currencies (USD, EUR, GBP, JPY, CAD, AUD) built into the tool. It does not fetch live prices. That makes it fine for a rough idea and useless for exact payments, which is exactly why this guide exists.
The four numbers behind any conversion
| Term | What it is | Who sets it |
|---|---|---|
| Mid-market rate | Midpoint of buy and sell prices in the wholesale market | The market, minute by minute |
| Spread or margin | How much worse than mid-market your provider's rate is | Your bank, card, exchange bureau |
| Fixed fee | A flat charge per transfer or withdrawal | Your provider |
| Percentage fee | A "foreign transaction fee", for example 2–3% on card payments | Your card issuer |
The total cost is the spread plus the fees. A provider advertising "no fees" may still charge through a wider spread.
A worked example
You owe a supplier €1,000. Suppose the mid-market rate is 1 EUR = 1.09 USD. The illustrative numbers below show how the same payment can cost different amounts.
| Method | Rate you get | Fees | Total in USD |
|---|---|---|---|
| Mid-market (no provider) | 1.090 | none | $1,090.00 |
| Provider A (0.5% margin, $3 fee) | 1.0955 | $3 | $1,098.50 |
| Provider B (2.5% margin, no fee) | 1.1173 | none | $1,117.25 |
| Card with 3% foreign transaction fee | 1.090 + 3% | 3% | $1,122.70 |
These figures are illustrative only, but the pattern is real: the difference between cheap and expensive options on one payment can be tens of dollars, and much more on larger amounts.
Dynamic currency conversion: say "local currency"
When you pay by card abroad, a terminal or ATM may offer to charge you in your home currency. This is dynamic currency conversion (DCC). It feels convenient, but the merchant's provider sets the rate, often with a large margin. In most cases you pay less by choosing the local currency and letting your own card issuer convert it.
How to compare providers properly
- Find the mid-market rate from a reputable source at the time you pay.
- Ask the provider for the amount the recipient will receive and the total you will pay, including all fees.
- Divide one by the other to get your real rate.
- Compare that real rate between providers, not the headline "zero fee" claims.
When a rough estimate is enough
For everyday planning, a fixed reference rate is perfectly fine:
- getting a feel for prices before a trip;
- deciding whether an overseas product is worth it;
- explaining a rough figure to a client before sending an exact quote.
That is what ToolMany's converter is for. Type the amount, pick the currencies, and read the estimate alongside the reference rate it used. In our tests, 100 USD converted to 92.00 EUR at the tool's built-in rate of 0.92. Real rates will differ.
Invoicing in another currency
If you bill clients abroad:
- state the currency explicitly on the invoice (USD, not just "quot;);
- agree who pays transfer fees, the sender or the receiver, to avoid short payments;
- if you convert amounts for the client's reference, label them "approximate".
The Invoice Generator lets you choose the invoice currency, so the total is shown in the currency you actually expect to receive.
Card, transfer or cash: how the costs differ
Different ways of moving money abroad carry costs in different places:
| Method | Where the cost hides | Good for |
|---|---|---|
| Debit or credit card abroad | Foreign transaction fee (often 0–3%) plus the card network's rate | Everyday spending on trips |
| ATM withdrawal abroad | Your bank's fee, the ATM owner's fee and the rate | Occasional cash |
| Bank wire transfer | Fixed sending fee, intermediary bank fees, and the bank's margin | Large, infrequent payments |
| Online money transfer service | Usually a small fee and a margin, both shown before you pay | Regular transfers and invoices |
| Exchange bureau cash | The spread between their buy and sell rates | Small amounts you need on arrival |
Cards with no foreign transaction fee are worth getting if you travel or buy from abroad often. For transfers, the cheapest option depends on the currency pair and the amount, so compare the total cost each time rather than assuming last year's choice is still best.
Why the rate keeps changing
Exchange rates move continuously while markets are open, in response to interest rates, trade, inflation and news. Over a week, a rate can easily move by a percent or two. That is why invoices and quotes in a foreign currency sometimes state a validity date ("this quote is valid for 7 days"), and why a calculator with fixed reference rates, like ours, drifts away from reality over time.
Checklist before paying abroad
- Choose local currency on card terminals and ATMs.
- Check your card's foreign transaction fee before travelling.
- For transfers, compare the total cost, not just the fee.
- Avoid exchanging cash at airports if you can; rates there are often poor.
- Keep receipts in case your statement shows a different amount than expected.
Frequently asked questions
Does ToolMany's converter use live rates?
No. It uses fixed reference rates built into the tool, so treat results as estimates.
What is the mid-market rate?
The midpoint between buy and sell prices in the wholesale currency market. Consumers rarely get exactly this rate.
Why does my card statement show a different amount than I expected?
The rate on the day the transaction was processed, plus your card's foreign transaction fee, is usually the reason.
Should I pay in my home currency or the local currency abroad?
Usually local currency. Paying in your home currency through dynamic currency conversion typically costs more.
Which currencies does ToolMany's converter support?
USD, EUR, GBP, JPY, CAD and AUD.
