Currency Converter
Convert between currencies using a rate you supply, including bank margin and fees — for everyday spending or sizing a forex conversion.
What the Currency Converter does
Converting currency multiplies (or divides) by the exchange rate, but the rate you are offered is rarely the mid-market rate quoted on financial sites. The difference is the provider's margin, and it is usually a larger cost than any advertised fee. Use "Divide by the rate" when your quote is expressed as units of your currency per unit of the other — the usual case when sizing a forex conversion rather than converting cash for a trip.
Formula
Mid-market amount = Amount × Rate (or Amount ÷ Rate for the divide direction)Effective rate = Rate × (1 − Margin) for multiply, Rate × (1 + Margin) for divideReceived = Amount at the effective rate − Fee
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Amount to convert | number | Yes | Accepts more than 0. |
| Exchange rate | number | Yes | How many units of the target currency one unit of the source buys. Accepts more than 0. |
| Direction | one of 2 options | Yes | — |
| Provider margin | % | Optional | The markup built into the rate you are offered. |
| Fixed fee | number | Optional | Accepts 0 or more. |
How to use it
- Choose Direction.
- Enter Amount to convert and Exchange rate.
- Optionally add Provider margin and Fixed fee.
- Select Calculate.
Worked example
Converting 1,000 units at a 1.2750 rate with a 3% margin and a 4-unit fee.
- Amount
- 1000
- Rate
- 1.2750
- Direction
- Multiply
- Margin
- 3
- Fee
- 4
Mid-market 1,275.00, but you receive 1,232.75 — a total cost of 42.25, about 3.3%.
Reading the result
- The gap between "at the mid-market rate" and "amount received" is the real, total cost of the conversion — margin and fee combined — and is the one number worth comparing across providers, regardless of how each one advertises its charges.
- A margin under 1% is close to what large institutions pay each other; retail travel and remittance providers commonly build in 2–4%, and it is rarely disclosed as a separate line.
- "Reverse rate" is the pure mathematical inverse of the entered rate, not what converting back would actually return — a real round trip applies its own margin and fee again in the other direction.
Assumptions and limitations
- The margin is modelled as a single flat percentage applied uniformly regardless of transaction size — some providers offer better rates at larger amounts, which this does not capture.
Common mistakes
- Comparing providers by their advertised fee alone. A "no fee" conversion with a 3% margin costs far more than a "$5 fee" conversion at the mid-market rate — the total cost line is what to compare, not the fee.
- Treating the rate on a financial news site as the rate you will get. That is the mid-market rate; every retail provider adds a margin on top of it.
- Picking the wrong direction for how your quote is expressed — multiplying a rate that should be divided (or vice versa) gives a result that is wrong by roughly the square of the real rate, not just slightly off.
Frequently asked questions
How do I compare providers fairly?
Ignore the advertised fee and compare only the final amount received. That single figure captures the margin and the fee together.
Should I use a card abroad or exchange cash?
Cards usually give a better rate than airport bureaux, but check for foreign transaction fees and always decline the merchant's offer to charge in your home currency.
Which direction should I use for sizing a forex trade?
Depends on how your quote is expressed. If the rate is "units of the other currency per unit of yours," multiply. If it is quoted the other way round, divide — most retail forex quotes are one unit of the base currency in terms of the quote currency, which is the multiply case.