How the conversion works
Every rate in this tool is stored against the US dollar, so any pair is one division away. If R(x) is the number of units of currency x that one dollar buys, then converting from currency A to currency B uses rate = R(B) / R(A), and the converted amount is simply the amount times that rate. Going the other way is the reciprocal.
Worked example: the built-in table holds EUR 0.87 and JPY 148 per dollar. To convert 250 euros to yen, rate = 148 / 0.87 = 170.115 yen per euro, so 250 EUR = 42,529 JPY. Check it by going through dollars: 250 / 0.87 = $287.36, and $287.36 x 148 = 42,529 yen. Same answer, which is what a consistent cross rate means.
The stored figures are reference rates, approximate, last reviewed Sep 2026. Major pairs can move 1% to 2% in a week and much more around central bank meetings, so for anything that matters - a wire, a tuition payment, an invoice - overwrite the rate box with the number your bank or broker actually quoted.
The rate you get is not the rate you see
Quoted mid-market rates sit halfway between what buyers and sellers pay. Consumers get something worse, and the gap is where the profit is. A US credit card with no foreign transaction fee usually settles close to the network rate, within about 1%. A card with a foreign transaction fee adds 3%. Airport kiosks and hotel desks routinely take 7% to 12%.
Watch for dynamic currency conversion. When a terminal abroad offers to charge you in dollars instead of the local currency, it is applying its own exchange rate with a markup of several percent. Always choose to be billed in the local currency and let your card issuer convert. ATM withdrawals follow the same rule, plus whatever flat fee your bank and the machine each charge.
For larger transfers, compare the all-in cost rather than the advertised rate: total dollars leaving your account against total units arriving. A service with a $0 fee and a 2% spread is more expensive on $5,000 than one with a $15 fee and a 0.4% spread.
Rounding and conventions
Most currencies here are quoted to two decimal places. The Japanese yen and the Korean won have no minor unit in everyday use, so the tool rounds them to whole units. Currency codes follow ISO 4217, the three-letter standard that appears on statements and wire instructions - USD, EUR, GBP and so on.
The quick table shows 1, 10, 100 and 1000 units in both directions. It is handy while traveling: memorize the 100-unit line and you can price almost anything in your head without pulling out a phone.