The board behind the teller shows three numbers next to your currency, and the one you actually get is the worst of the three. That gap is the whole economics of money exchange in Korea. It is also where the country's most misread piece of jargon sits — the "90% preferential rate" sign taped inside half the exchange windows in Seoul.
I assumed, the first time I saw one, that it meant something enormous. It does not. A preferential rate is a discount on the bank's margin, not on your money, and once you know that the rate board stops being intimidating.
Here is what those three numbers mean, which counters are actually open when you land, and how much won you need in hand before you can move — the practical shape of money exchange in Korea on day one.
The three numbers behind money exchange in Korea
Every Korean bank posts a reference rate for each currency. It is the market average rather than a price you can get — Woori Bank describes it as the real-time market rate, explicitly not the customer-facing posted rate.
Two prices sit around that midpoint. The cash selling rate is what you pay to walk away with won. The cash buying rate is what the bank gives you for won you hand back.
Cash carries the widest gap of any foreign exchange product, and the reason is physical: the bank has to hold, insure and ship actual notes.
Now the jargon. Woori Bank's own terms page defines it precisely — a preferential rate is a percentage applied to the difference between the cash rate and the reference rate, not to the amount you are changing.
So the arithmetic is small and specific. If the gap between the reference rate and the cash rate happens to be 20 won on a dollar, a 90% preferential rate leaves you paying 2 won of it. On a $300 exchange that is a coffee, not a plane ticket.
That cuts both ways. The signs are real, but chasing a marginally better one across three subway stops rarely pays for the fare.
Airport counters and airport banks keep different hours
This is the part that changes your first evening, and the two things are not the same. A bank branch at Incheon runs office hours. An exchange counter does not.
From Incheon Airport's own facility listing for Terminal 1:
| Where | Hours |
|---|---|
| KB counter, Arrival Hall B, 1F | 00:00-24:00 |
| Woori counter, Departure Hall 4, 3F | 00:00-24:00 |
| Hana counter, Departure Hall 2, 3F | 06:00-22:00 |
| Hana counter, Exit 4, 1F | 06:00-22:00 |
| KB, Hana and Woori branches | 09:00-16:00 |
Those branch hours are weekdays only. Land at 23:30 on a Saturday and the two round-the-clock counters are your entire menu — and one of them is upstairs in Departures.
Gimpo is thinner. The Korea Tourism Organization lists a single foreign exchange bank there: Shinhan, first floor of the domestic terminal to the right of the arrival gate, 09:00-16:00, closed weekends and public holidays (page last updated 21 August 2025).
Worth noting how I landed on those figures. Two different tourism pages gave conflicting hours for airport money exchangers, one saying 06:00-22:00 and another 06:00-19:30. When the operator publishes its own facility list, that is the one to read.
How much to change before you leave the airport
Enough to move and eat. Airport transport, one meal, and a transit card top-up is the honest floor.
Here is the part most guides state as fact and I could not verify: that airport rates are always worse than city rates. No official source I could open compares the two.
What the airport definitively sells you is hours — a counter open at midnight when every bank in Seoul is shut. So treat money exchange in Korea at the airport as a liquidity problem rather than a pricing one, and do the larger amount later where you can read more than one board.
Post offices exchange money, and old notes may not
Two facts from the Korea Tourism Organization that rarely survive into English guides.
Korea Post Bank exchanges currency and stays open until 16:30, half an hour past the usual bank window of 09:00-16:00 on weekdays. Post offices are also dense in residential neighbourhoods where bank branches are not, which quietly widens where money exchange in Korea is possible at all.
And older series notes may be refused at some locations. If your foreign currency has been sitting in a drawer since a previous trip, check it before you rely on it.
Where won cash is still the only thing that works
Korean notes come in 50,000 / 10,000 / 5,000 / 1,000 won, with coins at 500, 100, 50 and 10. Cards are accepted almost everywhere, which is precisely why the exceptions catch people out.
Two exceptions reliably catch them. Transit card top-up counters take cash only, and small independent traders often prefer it.
I have written separately about the T-money top-up cash wall and about where a foreign credit card actually fails in Korea. This article is the missing third piece — how you get the notes in the first place.
If you would rather carry one object than a wallet of notes, a Korea-issued prepaid card such as WOWPASS covers similar ground. I assessed that option honestly in the credit card article rather than repeating it here.
The 10,000 dollar line at customs
This one has teeth, and it applies in both directions.
The Korea Customs Service puts it plainly: bring in means of payment not exceeding USD 10,000 and you need no permission or declaration. Above that total you must report it — and Korean won notes and cashier's checks count toward the threshold, not just foreign currency.
The mechanics are specific. You mark yes on item 3 of the Traveler Declaration Form, enter the amount, hand it to a customs official, and receive a Certificate of Foreign Currency Declaration.
Keep that certificate. It is what lets you carry the money back out again.
Moving payment means across the border without filing the report is punishable by up to one year of imprisonment with labour, or a fine of up to 100 million won. The same USD 10,000 threshold applies on departure.
Doing this on arrival, in order
What you need: your passport, and foreign notes in decent condition — the tourism board's own warning about older series is worth heeding before you queue.
The order that works:
If it goes wrong: if the arrivals counter is shut, the 24-hour Departures counter is one floor up. If a machine refuses your card, that is a card-network problem rather than a currency one, and the credit card article covers it. If you simply run short in the city, remember banks close at 16:00 and post offices at 16:30 — buy your evening ahead of that.
Where to ask: the Korea Travel Helpline on 1330 answers in English, and the airport's own facility list is the live source for counter hours.
- Clear immigration and customs, declaring anything over the USD 10,000 line
- Find the arrivals-side counter — KB sits by Arrival Hall B on 1F and runs around the clock
- Change enough for transport, a meal and a transit card top-up
- Do the larger exchange later at a bank, a post office or a city window, with the reference rate in front of you
Wrapping Up
The thing I would go back and tell myself is that the rate board hides nothing. It is simply labelled for people who already have the vocabulary — three numbers, one of them theoretical, and a percentage that discounts a margin rather than a sum.
Get enough won at the airport to reach your bed, keep the customs threshold in mind if you are carrying serious cash, and do the rest in daylight. Rates move daily and bank policies change, so read the board posted on the day rather than any figure written in advance, this one included.
Photo credit Bank of Korea 20070103.jpg — Me, Public domain (Wikimedia Commons, https://commons.wikimedia.org/wiki/File:Bank_of_Korea_20070103.jpg) · Flagship Branch of Hana Bank.jpg — Hana Financial Group, CC BY-SA 3.0 (Wikimedia Commons, https://commons.wikimedia.org/wiki/File:Flagship_Branch_of_Hana_Bank.jpg)