Thailand's Lower Drink-Drive Limit for New Drivers

Thailand runs two drink-drive limits. The general one is 50 mg% (0.05% BAC). A much lower limit of 20 mg% — 0.02% BAC, which is close to zero tolerance — applies to drivers under 20, to holders of a provisional or temporary licence, to anyone driving a vehicle their licence does not cover, and to anyone driving with no valid licence at all.

The heading on this page says "young drivers" because that is what people search for, but the age rule is the least interesting of the four. The category that catches visitors is the third one, and it has nothing to do with age: a 45-year-old with a clean car licence, riding a rented scooter with no motorcycle entitlement, is on the 20 mg% limit exactly as a 19-year-old is.

• Lower limit20 mg% (0.02% BAC)
• General limit50 mg% (0.05% BAC)
• Set byMinisterial regulation published 20 September 2024
• Applies regardless of ageIf your licence does not cover the vehicle

Who the 20 mg% limit covers

The 2024 ministerial regulation on testing the alcohol content of drivers — signed on 3 September 2024 and published in the Royal Gazette on 20 September 2024 — defines the lower-limit group in four parts:

The wrong-category trap, in detail

Thailand issues separate entitlements for cars and for motorcycles, as most countries do, and the alcohol regulation keys the lower limit to whether you hold the right one for what you are driving. It does not ask whether the police stopped you, whether the rental shop asked, or whether the machine is small.

Work through the common cases:

• Home car licence, no motorcycle entitlement, riding a 125cc scooter. Lower limit. This is the single most common visitor situation in Thailand.
• Home car and motorcycle licence, but an IDP issued with only the car category ticked. Read your permit before you assume. The categories are printed inside and they are copied from what you asked for.
• Full home motorcycle licence and a matching IDP. General 50 mg% limit, assuming you are 20 or over.
• No licence at all, or a home licence that expired while you were travelling. Lower limit, plus the separate offence of driving without a licence.

If you are not sure which of these describes you, work through which licence you can use in Thailand and the international driving permit before you hire anything. It is a ten-minute check that changes your legal exposure on two fronts at once.

How little 20 mg% is

We do not publish drink-to-reading conversions and we do not have a calculator, for the reason given in full on Thailand's drink-driving limits: the only thing anyone does with an estimate is decide they are probably just under it, and the error bars are far too wide for that to be safe.

What can be said without a number is that 20 mg% is not a limit you can drink towards. It is well below what a single ordinary drink produces in most adults, and the practical reading of it is that a driver in the lower-limit group should treat drinking and driving as mutually exclusive on the same evening. That includes the following morning if the night was heavy — alcohol clears slowly, and no amount of coffee, food or sleep speeds it up.

Under 20, and the age question generally

The under-20 rule is straightforward: if you are under 20 on the day you are stopped, your limit is 20 mg%, whatever licence you hold. It applies to Thai and foreign drivers alike, because the regulation describes the driver rather than the licence's country of issue.

It also sits alongside — and should not be confused with — the separate question of how old you must be to hold a Thai entitlement in the first place, which depends on the vehicle and is covered in minimum driving age in Thailand. A young traveller can easily be in two of the four lower-limit categories at once: under 20, and riding a category their licence does not cover.

What follows if you are over the lower limit

Exactly the same as being over the general limit. There is no reduced offence for a low reading in the lower-limit group. Section 140 of the Act removes drink-driving from the fixed-penalty process entirely, so it cannot be dealt with by ticket at the roadside — the case goes to an inquiry officer and then to a court. A first offence carries up to a year and/or a fine of 5,000 to 20,000 baht, roughly £110 to £450 at the lower and upper ends, and the court must suspend the licence for at least six months or revoke it. The escalations where injury or death results are set out in drink-driving penalties in Thailand.

Refusal is not an escape either, and this is worth knowing before you are standing at a checkpoint at midnight: where an officer has reasonable ground to believe a driver is intoxicated and the driver refuses a test without reasonable justification, the Act presumes the offence was committed. Refusing a breath test in Thailand explains the mechanics.

The practical version

If you are in any of the four categories — and you very likely are, if you rented a scooter on a car licence — the rule to carry around is simple. Drink or ride, not both, on the same evening. Thailand makes that easy in a way most countries do not: Grab covers the cities and the tourist towns, motorbike taxis wait at the end of every soi, and a scooter left locked outside a bar overnight costs nothing. The only expensive option is the one where you decide, at one in the morning, that you are probably fine.

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