Currency Converter

It is the midpoint between the price at which banks buy a currency and the price at which they sell it, on the wholesale market where currencies actually trade. Nobody in retail is offered it. What you are given is that midpoint with a margin added — a card issuer might take a fraction of a percent, an airport bureau several percent, and a bank transfer often buries its margin in the rate rather than showing a fee. That is why a mid-market figure is a good reference and a poor prediction of your statement. To compare providers honestly, measure each quoted rate for the same pair against the mid-market number, then add any flat fee.

Almost always no. That offer is dynamic currency conversion: the terminal, not your card network, is choosing the rate. The margin is set by the merchant's processor and tends to be worse than your bank's, and the familiar-looking figure on screen is the sales pitch. Choose the local currency and let your card issuer convert, which is usually cheaper even after a foreign transaction fee. The same choice turns up at foreign checkouts online and on cash machines abroad. If a machine converts without asking, the receipt shows both amounts and the rate it used, which you can check afterwards.

The market that sets them closes late on Friday and reopens on Sunday evening, so published rates barely move across a weekend and most feeds carry Friday's figures forward. That does not make a weekend transaction predictable. Card networks apply their rate on the day the payment is processed, which can be a working day or two after you spent the money, so a Saturday purchase may settle at a rate you never saw. Some providers widen their margin over the weekend because they are carrying the risk of that gap. For a large transfer, the difference between Friday and Monday is worth waiting for.

Most tax authorities work from the rate in force on the date of the transaction rather than the date you do the paperwork. What counts as an acceptable source varies: several publish their own monthly or annual average rates that businesses are allowed to use for reporting, and applying one official source is usually safer than picking a favourable figure from a converter. Consistency is the part that matters — changing method between periods is what draws questions. For anything material, or where the gain or loss on the currency movement itself has to be reported, check the rule for your own jurisdiction.

The lists are built from whatever the rate feed publishes, so a currency absent from that table cannot be picked. A few categories tend to be missing or unreliable: currencies under strict capital controls, where an official rate and a street rate differ widely and only the official one is published; currencies of very small economies; and anything recently redenominated, where old and new units circulate under similar names. Precious metals and cryptocurrencies sit outside standard forex tables altogether. The codes follow ISO 4217, which explains the odd-looking ones — CHF for the Swiss franc comes from Confoederatio Helvetica, the country's Latin name.

The amount never leaves the page. The only thing sent anywhere is the three-letter code of the currency you are converting from, passed to this site's own route so it can request that base's table; the currency you are converting to is picked from a table you already hold, so it does not travel either. The conversion is one multiplication done in your browser. There is no account, nothing is written to storage, and reloading the tab returns you to the default pair. Each base's table is cached for an hour and shared between visitors, so much of the time nothing is asked upstream at all.

Two decimal places is a convention rather than a rule. ISO 4217 gives each currency a number of minor units: most have two, the Japanese yen and Korean won have none, and the Kuwaiti, Bahraini and Tunisian dinars have three. Formatting here follows your browser's locale and allows up to four decimal places, so a converted figure can carry more precision than the currency is ever paid in. The extra precision matters on small amounts, where one unit converted into a currency worth far more per unit would otherwise round away to nothing. When recording a real payment, round to the currency's own minor units.

On a mid-market table, near enough. Each table is quoted against a single base, so changing the From currency loads a different table rather than flipping a number, and the two directions should multiply back to roughly one — small discrepancies come from rounding at the fourth decimal place rather than from anything meaningful. The real market is not symmetric, because there are two prices, a bid and an ask, and you cross the spread whichever way you go. That is why changing money into another currency and straight back leaves you with less than you started with even when the market has not moved.