Understanding exchange rates and spreads
The rate you enter determines what the result means. The table contrasts the common rate types a consumer encounters; the gap between the mid-market rate and the rate you are offered is the real cost of the exchange.
| Rate type | What it is | Typical margin vs mid-market |
|---|---|---|
| Mid-market (interbank) | Midpoint of global buy/sell prices; the benchmark shown on financial data sites | None — the reference itself |
| Card network rate (Visa/Mastercard) | Rate applied to card purchases abroad, before any bank fees | Usually well under 1% |
| Bank transfer / retail rate | Rate your bank applies to transfers and cash exchange | Commonly around 1-5%, varies widely |
| Airport / tourist kiosk rate | Walk-up cash exchange | Often the widest spreads, sometimes 5-10%+ |
- Margins vary by institution, currency pair and amount; the ranges above are indicative conventions, not quotes. Always compare the rate you are offered against the current mid-market rate.
- Some card transactions abroad offer 'dynamic currency conversion' (paying in your home currency at the merchant's rate); the merchant's rate is typically worse than your card network's rate.
- Exchange rates move continuously during market hours, so a rate looked up in the morning may differ by the afternoon — enter a fresh rate for time-sensitive amounts.
- This tool performs arithmetic on a rate you supply; it does not provide financial advice, and past rates do not predict future rates.
What is an exchange rate conversion?
An exchange rate states how many units of one currency equal one unit of another. Converting is a single multiplication: the amount times the rate. If 1 US dollar buys 0.92 euros, then 100 dollars converts to 100 × 0.92 = 92 euros. The inverse rate — 1 divided by the rate — converts in the opposite direction: 1 ÷ 0.92 = 1.086957, so one euro buys about 1.09 dollars at the same rate.
The mid-market rate (also called the interbank rate) is the midpoint between the global buy and sell prices for a currency pair — the rate you see on financial data sites such as Google Finance, xe.com, Reuters or Bloomberg, and the fairest single benchmark for what a currency is worth. Banks, card networks and money-transfer services do not usually give consumers the mid-market rate: they apply a margin (spread) on top of it, typically anywhere from a fraction of a percent to several percent, sometimes alongside a fixed fee.
This converter deliberately asks you to supply the rate rather than fetching one. Live feeds go stale, differ between providers and hide the assumption inside the tool; entering the rate yourself makes the assumption explicit. To compare offers, run the conversion once with the mid-market rate and once with the rate you were actually quoted — the difference is the cost of the spread.
How to use this currency converter
- Look up the current rate for your currency pair from a source you trust — financial data sites publish the mid-market rate, and your bank or card statement shows the rate actually applied.
- Enter the amount you want to convert.
- Enter the exchange rate as units of the target currency per one unit of the source currency (for USD to EUR, a rate like 0.92).
- Read the converted amount, and use the inverse rate to sanity-check conversions in the opposite direction.
The formula behind currency conversion
The conversion is a single multiplication, and the inverse rate is the reciprocal of the rate you entered. The inverse is useful both for converting back and for catching an upside-down rate: if you accidentally enter EUR-per-USD where USD-per-EUR was intended, the inverse will look like the number you expected.
Worked example: converting 100 US dollars at a rate of 0.92 euros per dollar gives 100 × 0.92 = 92 euros. The inverse rate is 1 ÷ 0.92 = 1.086957 dollars per euro, so 92 euros converts back to 92 × 1.086957 ≈ 100 dollars.
Common mistakes
- Entering the rate upside down — USD to EUR needs euros-per-dollar (≈0.92), not dollars-per-euro (≈1.09); check the inverse rate output to catch this.
- Treating the mid-market rate as what you will actually receive — banks and kiosks add a spread, so the received amount is usually lower.
- Ignoring fixed fees — a transfer with a good rate but a flat fee can cost more on small amounts than a worse rate with no fee.
- Accepting dynamic currency conversion at the till — paying in local currency and letting your card network convert is usually cheaper.
- Using a stale rate — rates move continuously, so refresh the rate for anything time-sensitive.
Perguntas frequentes
Where do I find the current exchange rate?
Financial data sources such as Google Finance, xe.com, Reuters or Bloomberg publish live mid-market rates for any currency pair, and central banks publish daily reference rates (for example the European Central Bank's euro reference rates). For the rate that will actually be applied to your transaction, check your bank's published rates or the Visa and Mastercard rate calculators.
What is the mid-market exchange rate?
The mid-market rate is the midpoint between the buy and sell prices at which currencies trade on the global market. It is the benchmark rate shown on financial data sites and the fairest measure of a currency's value at a moment in time. Consumer transactions usually apply a rate slightly worse than mid-market, with the difference — the spread — being the provider's margin.
Why does my bank give a different rate than Google?
Google shows the mid-market rate, while banks and money-transfer services apply a margin on top of it, commonly ranging from under 1% to several percent depending on the institution, currency pair and channel — sometimes with a fixed fee added. Comparing your quoted rate against the mid-market rate reveals the true cost of the conversion.
How do I convert in the opposite direction?
Use the inverse rate, which this calculator shows automatically as 1 divided by your rate. If dollars convert to euros at 0.92, euros convert to dollars at 1 ÷ 0.92 = 1.086957. You can also re-run the conversion entering the inverse rate directly.
Why doesn't this calculator fetch live rates?
By design. A user-supplied rate keeps the arithmetic transparent, never goes stale inside the tool, and lets you model any scenario — today's mid-market rate, your bank's quoted rate, or a historical rate. Live feeds also differ slightly between providers, so a built-in feed would still not match what your bank applies.
Is 100 USD at a 0.92 rate exactly 92 EUR in practice?
Arithmetically yes: 100 × 0.92 = 92. In practice you would receive slightly less after the provider's spread and any fees — for example, a 2% margin turns the effective rate into about 0.9016, yielding 90.16 euros. Run the calculation with both the mid-market rate and your quoted rate to see the difference.
Referências
- European Central Bank — Euro foreign exchange reference rates (published each business day). ecb.europa.eu.
- Consumer Financial Protection Bureau (CFPB) — remittance transfer rules: disclosure of exchange rates and fees. consumerfinance.gov.
- Bank for International Settlements (BIS) — Triennial Central Bank Survey of foreign exchange markets. bis.org.