What dynamic currency conversion is

When you use a UK card in Thailand, the transaction is normally made in baht. Your card network — Visa or Mastercard — converts it into pounds at its own daily rate, and your bank adds its fee, if it has one. On a fee-free card, that's the whole story.

Dynamic currency conversion changes who does the conversion. The ATM operator or the shop's card machine recognises that your card is from the UK and offers to charge you in pounds instead. If you agree, the transaction is sent to your bank already in pounds, at an exchange rate chosen by the DCC provider — and your card's own rate never comes into it.

The "guaranteed rate" is guaranteed only in the sense that you know the pounds figure in advance. What you're not told is how far that rate is from the real one. In the EU and EEA, providers have had to show their markup over the European Central Bank's rate since 2020 — but those rules don't apply in Thailand, so the screen typically shows you only the final amount.

Why do machines and merchants offer it? Because the margin is shared between the DCC provider and the business offering it. It's a revenue stream for them, paid by you.

What accepting really costs

These are worked examples on a fee-free UK card, at ฿44.27 to the pound and a 7% DCC margin — in the middle of what travellers have reported at Thai ATMs:

Compare that with the ฿220 Thai ATM fee — about £4.97 — that most travellers worry about. Accepting the conversion on a single ฿20,000 withdrawal costs more than six times as much as the ATM fee itself.

Reported margins vary. Travellers have described rates around 8% to 9% worse at Krungsri, SCB and Bangkok Bank machines, 7.9% at a Kasikornbank machine in Chiang Mai, and 5.75% in other Kasikornbank reports. Shops and hotels using card-machine DCC can be similar. Whatever the exact figure, it's almost always worse than your card's rate.

The ATM screen: every way it's worded

Thai bank ATMs don't all use the same words, and some are designed to nudge you towards accepting. This is the screen at its simplest:

Here's how the two choices are commonly worded. The right-hand column is always the one you want:

If you press the wrong button by accident, cancel the transaction if the machine allows it and start again. If the cash has already come out, see below for what to do.

Card machines, hotels and restaurants

DCC is just as common when you pay by card in Thailand — sometimes more so, because a member of staff may make the choice for you. Watch for it in these situations:

• Hotel checkout. The final bill is often the biggest card payment of your trip. Ask for it in baht before the card goes in.
• Restaurants and bars where staff bring the machine to the table and hand it to you showing pounds.
• Shops and malls, particularly in tourist areas, where the terminal asks "THB or GBP?".
• Tour desks and dive shops, which may quote in baht but charge your card in pounds.
• Tax-free shopping and jewellery stores, where large amounts make the margin expensive.
• Taxi and transfer firms that take cards in tourist areas.

The rule is the same as at the ATM: always pay in baht. If the machine is handed to you already showing a pounds amount, say "Thai baht, please" and ask staff to cancel and start again. You're entitled to the choice — card network rules require DCC to be optional and the customer's decision, not the merchant's.

Contactless and Apple Pay or Google Pay don't protect you on their own — some terminals still ask the question before you tap. Glance at the screen before you pay.

Online bookings and apps

The online equivalent is a price shown in pounds because the website has detected you're in the UK — or a checkout box offering to "pay in GBP and avoid surprises". Thai airlines, hotels, tour operators, ferry companies and some booking sites do this.

Where you have a genuine choice of payment currency, pick Thai baht and let your fee-free card do the conversion. If the site only offers pounds, compare the price with the baht price on the Thai version of the site, or with the hotel's own website. Sometimes the difference is a currency conversion margin; sometimes the pounds price is genuinely fine. It's worth a minute's check on anything large.

One way to take the guesswork out of large bookings is to hold baht in a multicurrency account and pay from that balance. There's then no conversion at the point of payment at all — you converted earlier, at a rate you could see.

Ride-hailing and delivery apps such as Grab charge in baht in Thailand, so with a fee-free card there's nothing to do — but check your app's payment currency setting if you see pounds.

How to tell if conversion was applied

If you're not sure what you pressed, the receipt or your banking app will tell you:

To check how much it cost, look up the Visa or Mastercard rate for the same day using their online calculators, convert the baht amount yourself, and compare it with what you were charged. The difference is the cost of the conversion.

How to get your money back

If you accepted the conversion yourself, it's usually a done deal — it was your choice. But if you weren't given the choice, declined it and were converted anyway, or staff chose it for you, you may be able to get the extra back.

1. Act on the spot if you can. At a shop or hotel, ask staff to void the payment and redo it in baht before you leave.
2. Keep the evidence. Photograph the receipt, note the time and place, and screenshot the transaction in your app.
3. Work out the overcharge by comparing with the Visa or Mastercard rate for the same day.
4. Contact your card provider through its app or helpline and explain you weren't offered, or declined, payment in baht.
5. Ask for a chargeback. Card schemes have dispute rules for transactions charged in the wrong currency — Visa's is called "Incorrect Currency".
6. Use Section 75 for big purchases on a UK credit card if the merchant misrepresented what you were paying.

Some digital banks make this straightforward. Revolut, for example, says that if you rejected the conversion but it was still applied, it can raise a chargeback for you from the transaction in the app. Results aren't guaranteed, and an ATM withdrawal where you pressed "accept" is very hard to dispute — which is why reading the screen matters so much.

Is accepting conversion ever worth it?

Very rarely. Some UK banks don't charge their non-sterling fee when a transaction abroad is made in pounds. Barclays, for example, says its 2.99% fee doesn't apply if a merchant or ATM charges you in sterling — but it also points out that the provider then sets its own rate with a markup, which can cost more overall.

So in theory, if your card charges 2.99% and the DCC margin were smaller than that, accepting would be cheaper. In practice, reported DCC margins at Thai ATMs of 6% to 9% are two to three times that fee. The real answer is to avoid both: use a fee-free card and decline the conversion.

Even on a standard card, declining comes out ahead — and on a fee-free card the gap is larger still.

Cards that give you a fair rate in baht

Declining conversion only saves money if your own card converts at a fair rate with no added fee. These do:

For people living in Thailand

If you live in Thailand and pay mostly with a Thai bank card or Thai QR payments, DCC isn't an issue day to day — your transactions are in baht from start to finish. Where it still catches expats is on UK cards used for occasional large payments, and on transfers from the UK, where a bank's own exchange rate can hide a margin just like DCC does.

When you move larger sums — rent, school fees, a condo, a retirement visa deposit or pension income — the exchange rate matters far more than any ATM screen. That's worth getting right.