Most UK travellers know to decline the card machine when it offers to charge them in pounds. Far fewer think about it while sat at a laptop booking a month's accommodation, because by then the booking site has already made the choice for them.
The site sees a UK visitor, sets the display currency to GBP, and quotes you a comfortable, familiar number. There is no prompt to decline. There is no moment where you are asked. The decision was made before you arrived, and on a long booking it costs more than every ATM fee you will pay that month.
Disclosure: This article contains affiliate links. If you book through them we may receive a small commission at no cost to you. We use the booking platforms described here ourselves.
Key Takeaways
- Booking sites default to your home currency. That is a conversion, and someone is charging for it.
- Conversions done by anyone other than your card network typically run 3 to 8% above the mid-market rate.
- On a £900 monthly booking, a 5% conversion is £45. Repeat that every month and it becomes one of the largest avoidable costs on a long trip.
- The fix takes ten seconds: set the site's currency to the property's local currency before you search, not after.
- Check the quoted total against the mid-market rate yourself. If the site converts for you, the gap is the fee.
- This is a separate problem from the ATM and card terminal version covered in our ATM fees guide. Declining at the terminal does not protect you at the checkout.
Why the Booking Version Is Different
At an ATM or a card machine, dynamic currency conversion arrives as a question. A screen appears, it offers to bill you in pounds, and you decline. It is one decision at one moment, and once you know the rule you apply it every time.
Online there is no question. The site detects that you are in the UK, sets your currency to GBP, and presents everything that way from your first search onwards. Every price you compare, every property you shortlist, every total you budget against has already been converted. You never see the local currency figure unless you go looking for it.
That difference matters, because you cannot decline something you were never offered. It also means the cost stays invisible in exactly the situation where it is largest, which is a long booking.
The Three Places It Bites
The display currency. This is the selector in the corner of most booking sites. Left on GBP, every price you see has been converted for you. Change it to the property's local currency and you are looking at what the property actually charges.
Paying now, in pounds. If you choose a prepaid rate and the platform bills your card in GBP for a property priced in Thai Baht, a conversion happened somewhere, and it was not done by Visa or Mastercard at the rate your own card would have given you.
The property's terminal at check-in. If you chose to pay on arrival you are back in familiar territory, facing a card machine that may well offer you pounds. Decline it, exactly as you would at an ATM.
The third one is already covered by the standard advice. The first two are not, and they are where the money is on a long stay.
What It Actually Costs
The arithmetic is unglamorous, which is rather the point.
A family apartment in Southeast Asia at £900 for the month, converted at a 5% markup, costs you £45 you did not need to spend. Do that for six months and it is £270. For comparison, our entire connectivity spend for a month in Cambodia was £12.40.
It is also worse than it first looks, because the conversion lands on the largest single line in your budget. Accommodation is typically 30 to 50% of long-term travel spending, as we covered in our breakdown of what long-term travel actually costs. A few percent on your biggest cost beats a few percent on anything else.
How to Check It Yourself
You do not have to take anyone's figure on trust here, including ours. The method takes a minute:
- Find the property and note the total in local currency, with the site set to the property's own currency.
- Switch the site's currency to GBP and note the new total.
- Convert the local currency total at the mid-market rate, which is the number Google gives you if you search "1 THB to GBP".
- Compare. The gap between your calculation and the site's GBP figure is what the conversion costs you.
If the gap is under 1%, the site is being fair with you. If it is 3% or more, pay in local currency and let your card handle the conversion instead.
This is worth doing once per platform rather than once per booking. Platforms are consistent, so you learn the answer and then you simply know it.
Pay Now or Pay at the Property?
Setting the currency correctly turns this into a real decision rather than a trap, and it is worth thinking through properly on a long booking.
Paying now is usually cheaper on the headline rate and often non-refundable. It fixes your exchange rate on the day you book, which cuts both ways depending on what the pound does afterwards. It also means the money leaves your account months before you travel, which matters when you are living off a fixed runway.
Paying at the property preserves your cancellation flexibility and keeps the cash in your account until you arrive, but it exposes you to the terminal at check-in and to whatever the rate does between booking and arrival.
We generally pay at the property for anything we might realistically cancel, and prepay only when the discount is substantial and the plan is genuinely fixed. On a long trip, plans move more than you expect them to.
Your Card Still Matters
Setting the site to local currency hands the conversion back to your card, which is only an improvement if your card is any good at it.
A standard high street debit card charging around 2.75% in foreign transaction fees will undo most of what you just saved. Starling charges nothing on foreign transactions and gives you the Mastercard rate. Wise lets you hold the local currency in advance and convert when the rate suits you, which is what we do when the pound is strong.
The full comparison is in our Starling vs Wise vs Revolut verdict, and the detail on Wise specifically is in our Wise card review.
The two decisions work together. Local currency at the booking site, then a card that does not charge you for the conversion. Get one right and not the other and you have solved half the problem.
What We Actually Do
We set every booking site to local currency the first time we use it, before searching for anything. It persists in the account settings, so it is a one-off job rather than a discipline you have to remember on every booking.
We pay at the property where we can, in local currency, on a Starling card. Where we prepay, we check the GBP total against the mid-market rate first, using the method above.
For longer stays we hold the local currency in Wise ahead of time, which takes the exchange rate question out of the booking entirely. That is not sophisticated currency speculation. It is just not being forced to convert on whatever day the booking happens to fall.
Who This Is and Isn't For
If you are booking a week's holiday, this is worth knowing but it does not need a spreadsheet. A few percent on a £400 booking is real money, but it is not going to change your trip.
If you are booking accommodation month after month for a year, this is one of the highest value ten seconds you will spend. It costs nothing, it applies to your largest expense, and unlike most travel savings advice it does not ask you to accept anything worse in exchange.
