You looked up the rate on your phone this morning. It said one thing. Now you’re standing at a counter, or staring at a banking app, and the number in front of you is worse. Did somebody make a mistake? Usually not. Two different things share the name “exchange rate”, and they were never meant to match.
One is a reading, the other is a price
The figure you see when you search a currency pair online is a reading. It tells you roughly where the market is trading. Think of it as the temperature outside: useful, accurate enough, but you can’t buy any of it.
What your bank quotes is a price. It’s what the bank will actually pay or charge you to do the swap, and it has the bank’s running costs and profit baked in.
So the gap isn’t a glitch. It’s the bank’s side of the deal showing up in the arithmetic. How big it is depends on a handful of things, and we’ll go through them one at a time.
The market has no single price
Currency doesn’t trade on one exchange with one ticker, the way a single company’s shares might. It’s an over-the-counter market, a web of banks and dealers quoting each other all day. The Bank for International Settlements, which surveys this every three years, found average daily turnover of about 9.6 trillion US dollars in April 2025, with the dollar on one side of 89.2% of trades.
That volume matters here because of what it implies. At any given second, there are many slightly different quotes floating around. A website or app that shows you one number is boiling that down into a representative figure. Perfectly sensible. But it’s a summary, and a summary is not an offer.
Official reference rates work the same way. The European Central Bank publishes euro reference rates once each working day, around 16:00 CET, based on a procedure that aims to reflect market conditions at 14:15 CET. It labels them as being for information purposes only and says that using them for transaction purposes is strongly discouraged. If the central bank itself says “don’t trade on this”, the number on your search page deserves the same respect.
Reason one: the bank quotes two prices
Back to the counter. A bank that deals in currency has to make money on the exchange, and the cleanest way is to buy from you cheaper than it sells to you. Two prices, one on each side of the middle.
Online, the reading sits in the middle. Your bank’s price is on one side of it, depending on which way you’re going. Which is why converting pounds to dollars and back again, on the same day with the market not moving at all, leaves you short.
Here’s an illustrative round trip. All numbers made up:
- Reading online: 1 GBP = 1.3000 USD.
- Bank buys pounds from you at 1.2610 (3% under the middle). You hand over 2,000 GBP and get 2,522.00 USD.
- Bank sells pounds back to you at 1.3390 (3% over the middle). Your 2,522.00 USD buys 1,883.50 GBP.
- Market never moved, yet you’re 116.50 GBP down, or 5.83%.
Three percent each way is a hypothetical, picked to make the sum easy to follow. Real margins vary by bank, currency and channel. The Financial Consumer Agency of Canada, looking at bank fees, reports that currency conversion markups typically range from about 1% to 4% against the mid-market rate. And it notes that banks tell you the rate applied but not the markup, which has to be estimated by comparing the two. Hence the feeling that something is hidden. It is, a bit. Not illegally, just unlabelled.
Reason two: time, and whether the quote is firm
Markets move. Seconds matter in the dealing room, and minutes matter even to a traveller. A rate you noted at breakfast can be stale by lunch.
Banks also handle timing in their own ways. Some update the rates on their branch boards or apps several times a day, others less often. Some lock a rate for a short window. Card payments are a separate matter: the rate may be fixed when the transaction is processed rather than when you tapped, so the figure on your statement can differ from the one you saw at the till. Policies differ, and your card agreement should say how yours works.
An indicative rate on a website is a guide. A firm rate is one the provider has committed to for a stated period. Many apps lock a rate when you confirm; some give you a countdown. Some only show an estimate and settle later. The words to look for are “guaranteed”, “locked” and a time limit.
A fair test: take a screenshot of the converter at the moment you’re quoted, not an hour earlier. Even then, expect a small drift. A 0.2% move on 2,000 pounds, at the earlier example’s rate, is about 5.20 dollars. That’s noise, not a scandal. The 78 dollars lost to the margin in the first leg is a different matter.
Reason three: the channel you use
Same bank, same currency, same minute, different rate. It happens often enough that it’s worth stating plainly.
Cash at a branch, a card payment and an international transfer all run through different machinery, and each has its own costs. The price you’re quoted may well reflect that. The only way to know is to ask for the rate and any fee in each channel before you commit.
Amount matters too. Providers can price differently depending on how much you convert, so a quote for a small amount may not hold for a large one. Ask whether the rate changes with the size of the transfer.
How to measure the gap yourself
You don’t need a finance degree. Three steps:
- Open a converter at the same moment as your quote. For pounds to dollars, our GBP to USD page works.
- Multiply your amount by the mid-market figure. That’s your ideal number.
- Subtract what the provider is actually giving you, after any fee. Divide that difference by the ideal number. That’s your real cost as a percentage.
For 2,000 pounds at the made-up 1.3000, ideal is 2,600 dollars. A bank giving 2,522 is 78 dollars short, or 3.0%. If there’s also a flat fee, add it to the shortfall before you divide. Do this for two or three options and the winner is obvious, whatever the marketing says.
When a gap is normal, and when to push back
A few percent between a consumer rate and the reference rate is not a sign of anything shady. It’s how the retail business is priced. What deserves a question is a gap that’s much larger than the alternatives you can find, a rate that isn’t disclosed until after you commit, or a “no fee” claim sitting beside a rate that looks poor.
Asking directly works too, and it costs nothing: “What’s your margin over the mid-market rate on this?” Not every staff member will have the number. But the question tells them you’re comparing, which tends to focus the mind.
Use a converter for what it’s good at: knowing the ballpark, spotting a bad quote, working out what something costs abroad. The converter on our US dollar page is refreshed hourly, so treat it as a guide rather than a quote. Then get the real price in writing, in the currency your recipient will get, before the money moves. This guide is general information, not financial advice, so check the terms with your own provider.
Sources
- OTC foreign exchange turnover in April 2025 (Bank for International Settlements)
- Euro foreign exchange reference rates (European Central Bank)
- Review of banking fees in Canada: currency conversion markup (Financial Consumer Agency of Canada)
Checked: November 2026
