How Exchange Rate Spreads Are Set

Currency is never exchanged at the rate published in financial media. The difference is a spread, and its size is a reliable indicator of the conditions at the point of exchange.

Two prices exist, not one

Any currency dealer quotes a buy rate and a sell rate, and the gap between them is where the business earns its margin.

The published mid-market rate sits between the two and is the rate at which large institutions trade with each other in volume.

A retail customer is on the wrong side of both, and the distance from the mid-market rate is the real cost of the transaction regardless of advertised commission.

Spread reflects volume and risk

Widely traded currency pairs move constantly and in enormous volume, so a dealer can offset a position immediately and needs only a thin margin.

Thinly traded currencies carry inventory risk, since the dealer may hold the notes for days before selling them, and the spread widens to cover that.

Physical cash costs more than an electronic transfer, because notes must be transported, insured, stored and eventually repatriated.

Location determines competition

An airport bureau serves customers who cannot easily go elsewhere, and the spread reflects that captivity rather than the underlying currency.

A city centre with several exchanges within sight of each other produces visibly narrower spreads, because customers can compare in a minute.

Zero commission signs usually indicate the margin has been moved into the rate, which is harder to compare and therefore preferred by the dealer.

Cards apply their own layers

Card transactions convert at a network rate close to mid-market, but the issuing bank may add a foreign transaction percentage on top of it.

Cash withdrawal abroad can attract a machine operator fee, an issuer fee and a conversion margin, each disclosed at a different point in the process.

The total cost is therefore assembled from several small charges, which is why comparing a single advertised figure rarely identifies the cheapest method.

Comparing correctly requires one calculation

The only meaningful comparison is how much destination currency is received for a fixed amount of home currency, after every fee.

Doing that calculation once for two or three methods before travelling settles the question for the whole trip, since the ranking rarely changes.

Leaving some exchange until arrival is normally cheaper than doing all of it at a departure airport, where the spread is widest by design.