Currency Conversion Basics: Exchange Rates & Spreads

Every time you swipe a card abroad or send money across a border, two prices exist: the rate banks trade at, and the rate you actually get. The gap between them is where currency conversion gets expensive — and confusing. This guide walks through the moving parts so you can read any quote critically.

The Building Blocks of an Exchange Rate

TermWhat It MeansTypical Range
Mid-market rateTrue interbank midpointWhat Google shows
BidWhat a dealer will pay youBelow mid
AskWhat a dealer charges youAbove mid
SpreadAsk minus bid, as % of mid0.1%–3%
MarkupProvider's hidden margin0.5%–5%
PipSmallest standard move0.0001 for most pairs

Mid-Market vs Retail

The interbank market deals in millions of units, and major pairs trade with razor-thin spreads. Retail customers move smaller amounts and are charged for the convenience. A retail provider quoting EUR/USD might use a mid of 1.0850 but show you 1.0800 to buy euros — that is a 0.46% markup baked into the rate, on top of any visible fee.

Card networks (Visa, Mastercard) and travel cards usually publish their daily rate openly, often within 0.2–0.5% of mid-market. Your bank may then add its own foreign-transaction fee of 1–3%. Cash exchanges at airports are the worst case — spreads of 5–10% are common.

Spotting the Real Cost

  1. Look up the mid-market rate on a neutral source like Google or XE.
  2. Get the quote for the exact amount you want to convert, including all fees.
  3. Divide the amount received by the amount sent and compare to mid.
  4. Whatever percentage gap you see is your total cost, no matter how the provider labels it.

Need to Convert Other Units?

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Frequently Asked Questions

The interbank midpoint between bid and ask — the 'real' rate before any markup.
The gap between buy and sell prices. Retail spreads are typically 0.5%–3%.
Each adds its own margin. Compare the final amount received, not advertised fees.
By dividing two pairs that share a currency — e.g. EUR/JPY = (USD/JPY) ÷ (USD/EUR).
For most transfers, fees matter more than timing. Use forward contracts for large sums.