Changing riyals, dirhams and dinars in Thailand.

Six currencies, two different behaviours

The Gulf currencies our clients arrive with do not all behave the same way against the baht, and the distinction is worth a paragraph because it explains most of what you will see on a rate board. The Saudi riyal and the UAE dirham are pegged to the United States dollar at fixed rates that have held for decades. The Bahraini dinar and the Omani rial are also maintained against the dollar. The Qatari riyal is likewise dollar linked. The Kuwaiti dinar is managed against an undisclosed basket of currencies in which the dollar is the dominant component, which makes it the only one of the six that moves independently to any noticeable degree, and it remains the highest valued of the six in nominal terms.

The practical consequence is that when you change riyals or dirhams for baht, you are, in almost all cases, really watching the dollar against the baht. If the dollar strengthens against the baht, your riyal buys more baht; if it weakens, your riyal buys fewer. Nothing about Saudi or Emirati monetary policy is doing the work in that moment. This is useful because it means you can follow one relationship rather than six, and because it explains why every Gulf currency on a Bangkok rate board tends to move in the same direction on the same morning. We are describing mechanics here, not forecasting anything: we do not advise on when to change money and no honest office would.

The cross rate problem, and why dollars sometimes win

A Bangkok exchange counter does not hold a deep market in Omani rials. It holds a deep market in dollars, euros, yen, pounds, yuan and Singapore dollars, and it prices the Gulf currencies as secondary lines. That shows up as a wider spread: the gap between the counter's buying and selling rate on a Kuwaiti dinar or a Bahraini dinar will typically be wider than on a dollar, because the counter carries inventory risk on a note it may not resell for a fortnight. The dirham and the riyal, which arrive in volume with Gulf travellers, are usually quoted more tightly than the smaller currencies.

Some travellers respond by carrying dollars instead. Whether that helps depends on what buying dollars costs at home, since you then pay two spreads rather than one. For dirhams and riyals, direct conversion in Bangkok is usually competitive enough that the double conversion is not worth the trouble. What is not in doubt is that a Gulf note of any of the six is accepted at the major exchange chains in Bangkok and around Sukhumvit Soi 3 and 3/1. Outside Bangkok, and particularly on the islands, assume less.

Where the rates are actually good

Thailand's retail exchange sector is regulated by the Bank of Thailand, and licensed operators must display authorisation. The competitive counters are the dedicated exchange chains, which occupy small shopfronts in the malls, on the main Sukhumvit sois, near the Skytrain stations and in the tourist districts, and which publish their boards openly and compete on them. Bank branches are respectable but usually a little behind the specialist chains. Hotel front desks are the most expensive convenient option anywhere in the country, sometimes by a margin that surprises people, and they are transparent about being a convenience rather than a market.

Around Sukhumvit Soi 3 and Soi 3/1, the Middle Eastern quarter our guides call the Nana corridor, there is a cluster of long established money changers who deal in Gulf currencies daily and price them accordingly. For a family based at Bumrungrad or in the Ploenchit corridor, this is the most convenient competitive market in the country, and it is a five minute walk rather than a journey. Compare two boards before committing, as the counters sit close enough together to make that trivial. In Phuket, the exchange booths along the Patong and Kata beach roads are numerous and variable; in the resort areas of Samui and Krabi, thinner still. Change in Bangkok when you can.

The airport question, answered honestly

Airport exchange counters, at Suvarnabhumi and at Phuket, offer worse rates than the city. This is not a scandal; it is what airport retail rent and a captive audience produce everywhere in the world. Suvarnabhumi is better than many international airports in this respect, partly because several of the same chains that compete in the city operate there and partly because the counters beyond the arrivals hall, on the public levels and at the rail link, price more keenly than the ones you meet first. But the city is still better.

The sensible practice is therefore to change a small working amount at the airport, enough for the car, a first meal, tips for the porters and a contingency, and to do the substantive conversion in the city within the first day or two. If a car and driver has been arranged in advance, as it is for most of our clients, the immediate cash need is small enough that a token amount will do. Do not, on the other hand, arrive with no baht at all: not every situation at the end of a seven hour flight is a card situation, and a grandmother waiting in an arrivals hall is not the moment to discover that a machine is out of service.

Reading a rate board without being caught

A rate board shows two numbers per currency, a buying rate and a selling rate, and the one that applies to you when you hand over riyals is the counter's buying rate for that currency. Read the correct column. Boards sometimes show different rates for different denominations of the same currency, with larger, cleaner notes attracting a better rate than small or worn ones, which is normal and worth knowing if you are carrying a mixture. Some counters advertise a headline rate and then apply a commission or a fixed fee; others build everything into the rate.

The question that cuts through all of it is simple and should be asked every time: how many baht will I receive in total for this amount, after everything. Ask it before you hand anything over, and treat the answer, not the board, as the price. Then count the notes at the counter before you step away, and check the receipt. Legitimate operators expect all three of these behaviours and are unbothered by them. An operator who is impatient with a customer counting money is telling you something useful.

Dynamic currency conversion: always refuse

At a card terminal, at a cash machine, and increasingly at an online checkout, you will be offered the option to be charged in your home currency rather than in baht. The screen presents it as helpfulness, sometimes with a locked in rate and a reassuring line about knowing exactly what you will pay. This is dynamic currency conversion, and the answer is always to decline it and choose Thai baht.

The reason is straightforward. When you pay in baht, the conversion is performed by your own card network and your own issuing bank, at their rate, plus whatever foreign transaction fee your bank charges. When you accept conversion at the terminal, the rate is set by the merchant's payment processor, which has both the ability and the commercial motive to set it in its own favour, and your bank may still apply its foreign transaction fee on top. The margin taken is not trivial and it applies to the whole transaction. On a hospital deposit, a jewellery purchase or a hotel bill for a large family, choosing the wrong button costs real money.

The same logic applies at cash machines, where the offer appears as a choice between a displayed conversion rate and proceeding without conversion. Proceed without. If a cashier has already set a terminal to your home currency, it is entirely reasonable to ask to be charged in baht and to have the transaction re entered.

Changing baht back, and what to do with the remainder

Baht left over at the end of a stay can be changed back at the same counters, at their selling rate, which means you pay the spread a second time. On a modest sum that is not worth a special journey; on a large one it is worth doing in the city rather than at the airport, and worth avoiding altogether by not over converting in the first place. A family that returns to Thailand every summer, which describes a good number of our clients, often simply keeps a working amount of baht at home for the next trip, and there is nothing wrong with that provided the amount is sensible and, if it is being carried across a border, it is declared where the threshold requires it.

Note also that limits apply to how much Thai currency may be taken out of Thailand, separately from the foreign currency declaration rules, and that the allowance differs by destination. We print no figures, because they change and a stale number is worse than none. Check with the Customs Department of Thailand before leaving with any substantial amount of baht, and check the receiving country's rules too. Our guide to currency declaration deals with both sides of that journey.

Exchange rates, commissions and the licensing status of individual operators change constantly, and nothing in this guide is a rate quotation or a recommendation to convert at any particular time. Verify that a money changer is licensed with the Bank of Thailand, confirm limits on taking Thai baht or foreign currency out of the country with the Customs Department of Thailand, and confirm your own country's rules with its customs authority. For anything touching the treatment of converted funds, take advice from your own bank and your own tax adviser.

This briefing is general information, not legal, tax or investment advice. Thai rules change frequently and individual cases differ. Verify current requirements with the relevant authorities, including the Immigration Bureau, the Board of Investment, the Land Department, the Department of Business Development and the Revenue Department, and take advice on your own facts before acting.