What the rate does not cover
The exchange rate is one line on a transaction that usually has several.
- The bank's margin on the rate itself, typically one to three percent for an outward transfer.
- A transfer fee, and sometimes a separate SWIFT charge.
- Tax collected at source on remittances above the current threshold, which varies by purpose.
- Correspondent bank charges, deducted in transit, which is why the amount arriving is sometimes less than the amount quoted.
- Form A2 and purpose codes, which your bank will require and which determine the tax treatment.
Ask for the all-in amount that will arrive, not the rate. Providers compete on the number that is easiest to advertise, which is rarely the one that matters.
Where the rates come from
The European Central Bank publishes a set of reference rates against the euro on each working day, at around 16:00 Central European Time. They are drawn from a regular concertation procedure between central banks and are intended as a reference, which is exactly what a converter needs.
This page fetches those rates when it loads and calculates everything else from them. A pair that does not involve the euro is worked out through it, which is standard practice and introduces no meaningful error at any amount you are likely to be converting.
If that request fails, or you are offline, a rate table stored in the page is used instead and the line under the result says so along with the date it was captured. A stale rate presented as a live one would be worse than no converter at all, so the page never does that quietly.
There is no publication at weekends or on European public holidays, so a Saturday reading shows Friday's rate. That is the reference rate, not a market that has stopped moving.
What different providers actually charge
Every one of these quotes a rate below mid-market. The spread is the cost, whether or not a fee is also shown.
The pattern is consistent: the more convenient the option, the wider the spread, and the options that hide the cost entirely in the rate are the expensive ones. A provider that shows a fee and quotes close to mid-market is usually cheaper overall than one advertising no fee at all.
Dynamic currency conversion deserves its own mention because it is the easiest to avoid. When a card machine or a website abroad offers to charge you in your home currency, it is offering to do the conversion at its own rate. Decline it and pay in the local currency every time.