Why your card charges more than the exchange rate
The number you get by multiplying by the exchange rate and the number that lands on your card statement are about 2% apart.
$49.99 times 1,380 KRW is 68,986 won, but the statement says something closer to 70,000. The rate was not wrong: things get added in between.
The multiplication is the easy part
49.99 × 1,380 KRW = 68,986 KRWThat 1,380 is the mid-market rate. It's the number in the news, and it's close to the wholesale price banks use with each other.
You can't buy at that price.
What actually gets added
| Roughly | |
|---|---|
| Mid-market rate | The baseline |
| + your card issuer's currency conversion fee | 0.2–0.3% |
| + the network's fee (Visa / Mastercard) | 1.0–1.1% |
| + a foreign transaction fee, if your issuer charges one | 0–0.3% |
Together that's 1.5–2% above the rate you looked up. It becomes visible on larger amounts: spend $1,000 abroad and you're handing over $15 to $20 you never saw on a price tag.
The rate is not from the day you bought
This is the second trap. The rate applied is the one from the day your card issuer settles the transaction, not the day you clicked buy. That is usually a few days later.
So the statement arrives and doesn't match what you calculated. The rate moved in between. A 1% move over a few days is unremarkable, so a difference of a few thousand won is normal.
Say no to being charged in your own currency
Some overseas checkouts ask whether you would like to pay in your home currency instead. Decline.
If you accept, the merchant's payment processor picks the rate, and that rate has 3–8% built into it. Compare that with your card's 1.5% and it's several times worse.
Paying in the local currency and letting your card issuer do the conversion is always cheaper. The whole trick rests on the convenience of seeing a familiar currency on screen.
The rate changes several times a day
It moves continuously while markets are open. For figuring out roughly what a purchase will cost, though, the once-a-day published rate is plenty. If a few units of currency decide whether you buy, the exchange rate is not really your problem.
Meaningful movement happens over weeks, not hours. For a large purchase that isn't urgent, waiting a few days genuinely does something.
What this does not cover
- Customs duty and import VAT: in Korea these kick in above $200 for goods from the US and $150
from elsewhere, and they are calculated separately from the exchange rate
- Package forwarding fees
- Cash rates at a bank counter or exchange booth: a different fee structure again
- Whether the rate will go up or down. Nobody knows
The converter carries won, dollar, euro, yen, yuan, pound and Australian dollar. Choose an amount and a currency and it does the arithmetic.
Two caveats before you lean on the number. The rate is the European Central Bank's published reference, so none of the fees above are baked in; add roughly 2% to guess at a card charge. And it fetches once a day, because that reference is published once a day.
Almost every box here runs with no internet at all. This one is an exception, along with the dictionary and the radio. When it cannot reach the source it falls back to the last rate it received, labeled with the date that rate is from.