Currency Calculator
Convert currency with a manually entered exchange rate.
About the Currency Calculator
Convert an amount between currencies at a rate you supply. Rates move constantly, so this uses the figure you enter rather than pretending to be live.
How to use it
- Enter the amount.
- Enter the exchange rate.
- Read the converted total.
The formula
Conversion itself is one multiplication. Everything that makes currency confusing happens around it, in the gap between the rate you read and the rate you get.
Converted = Amount × Rate
Inverse rate = 1 ÷ Rate
Cross rate: A→C = (A→B) × (B→C)
Because you enter the rate yourself, this calculator gives exactly the number your quote implies — no live feed, no tracking and no invented spread. That is deliberate: the rate you are actually offered is rarely the one on a news site.
The published figure is the mid-market rate, halfway between what buyers and sellers are quoting. Nobody retail trades at it. Your provider takes a margin by shifting the rate, which is why comparing on 'no fee' claims alone is misleading — the fee is often inside the rate.
Worked examples
| Provider type | Typical margin over mid-market | Cost on $1,000 |
|---|---|---|
| Interbank / mid-market | 0% | $0 — the reference point |
| Online specialist | 0.4% – 1% | $4 – $10 |
| High-street bank | 2% – 4% | $20 – $40 |
| Airport bureau | 7% – 15% | $70 – $150 |
The spread between the top and bottom rows is the entire lesson. The same $1,000 can cost you nothing or $150 depending purely on where you exchange it, and the airport bureau advertising 'no commission' is usually the most expensive option in the building — because the charge is built into a rate that looks like a rate. Always compare the final amount received, never the fee.
Common mistakes
- Comparing on fees instead of the final amount. A zero-fee provider with a 4% rate margin costs more than a 1% provider charging a small flat fee. The only fair comparison is how much arrives at the other end.
- Accepting dynamic currency conversion. When a foreign card machine offers to charge you in your home currency, it is applying its own rate, typically 3% to 6% worse. Always choose the local currency.
- Inverting the rate by mistake. If 1 USD buys 0.92 EUR, then 1 EUR buys 1.087 USD. Applying the wrong direction produces an answer wrong by the square of the rate — noticeable, but not always obviously so.
- Using a stale rate for a large transfer. Rates move continuously. For a house deposit or similar, the rate at the moment of execution is what counts, not the one you checked yesterday.
Terms explained
- Mid-market rate
- The midpoint between buy and sell prices in the wholesale market. The honest reference, and not what retail customers receive.
- Spread
- The gap between the buying and selling rate. Where a provider's margin usually sits.
- Base and quote currency
- In EUR/USD, the euro is the base and the dollar the quote. The rate says how much quote currency one unit of base buys.
- Cross rate
- A rate between two currencies derived through a third, usually the dollar.
- Dynamic currency conversion
- Being charged in your home currency abroad, at the merchant's rate. Almost always worse than declining it.
- Interbank rate
- What banks charge each other. The closest thing to a true rate, and unavailable to retail customers.
Common questions
- Why does this not fetch live rates?
- So the result matches exactly the rate you were quoted, with no invented spread and no tracking. Enter the rate your provider offers and you see precisely what you will receive.
- Why is my bank's rate worse than the one online?
- Published rates are mid-market, halfway between wholesale buying and selling. Providers make their margin by shifting that rate, so retail customers always receive something slightly worse.
- What is the cheapest way to exchange money?
- Generally an online specialist or a card with no foreign transaction fee, at 0.4% to 1% over mid-market. Airport bureaux are consistently the most expensive.
- Should I let a shop abroad charge me in my own currency?
- No. That is dynamic currency conversion, and it applies the merchant's rate rather than your card issuer's — usually 3% to 6% worse. Always pay in the local currency.
- How do I invert a rate?
- Divide one by it. If a dollar buys 0.92 euros, a euro buys 1 ÷ 0.92 = 1.087 dollars.
- What is a cross rate?
- A rate between two currencies calculated through a third. Multiply the two rates: if A buys 2 B and B buys 3 C, then A buys 6 C.
- Why do rates change constantly?
- Currencies trade continuously in the largest market in the world, moving on interest rates, inflation, trade flows and sentiment. Small movements are constant and mostly irrelevant to everyday amounts.
- Is it worth timing a transfer?
- For everyday sums, no — the spread you pay dwarfs any likely movement. For very large transfers, a forward contract that fixes a rate in advance is the usual approach.