FAQ | Alcohol Limit Thailand, Drink Driving Penalties & BAC Rules

The legal alcohol limit in Thailand is 0.05% — equivalent to 50 milligrams of alcohol per 100 millilitres of blood (50mg%) — for most drivers who have held a full licence for more than five years. This is the same level as most of Europe and Australia, and is set by the Thai Land Traffic Act.

A stricter 0.02% (20mg%) limit applies to drivers under 20, holders of a provisional or under-5-year licence, and anyone driving without a licence or while suspended. For these drivers, even one drink can put you over. Going over the limit carries up to one year in jail, a ฿5,000–฿20,000 fine, and licence suspension of at least six months. If you plan to drive, the safe amount is zero.

Drink-driving penalties in Thailand start at up to 1 year in jail, a fine of ฿5,000–฿20,000, and a licence suspension of at least 6 months (the court can revoke the licence). A repeat offence within two years raises this to up to 2 years' jail, a ฿50,000–฿100,000 fine, and a suspension of at least one year.

Penalties escalate sharply if you cause harm. Causing injury brings 1–5 years and ฿20,000–฿100,000; serious injury 2–6 years and ฿40,000–฿120,000; and causing death 3–10 years, ฿60,000–฿200,000, and immediate licence revocation. Police prosecute on the spot with no verbal warning, and tourists driving on a foreign or international licence face exactly the same penalties as Thai nationals.

Thailand applies a reduced 0.02% (20mg%) limit to higher-risk groups of drivers. This stricter threshold covers anyone who is under 20 years old, holds a provisional licence or a licence held for less than five years, or is driving without a valid licence or while suspended or revoked.

At 0.02%, the margin is tiny — barely a single standard drink can put you over, and in practice the safest assumption for anyone in these groups is zero alcohol before driving. The reduced limit was introduced to cut the high crash rate among young and inexperienced drivers. If you do not clearly fall into the general (over-5-year licence) category, you should treat 0.02% as your limit, not 0.05%.

No. Under Thai law, refusing a breath or blood alcohol test is treated as an admission of drink-driving. You do not avoid the penalty by refusing — the law presumes you were over the limit, and you face the same consequences as if you had tested positive: up to 1 year in jail, a ฿5,000–฿20,000 fine, and licence suspension.

Thai police run roadside breath-test checkpoints — locally called "เป่า" (blowing) — very frequently, especially at night, near entertainment venues, and during the Songkran and New Year holidays when enforcement is nationwide. Recent policy is to prosecute immediately with no verbal warning. Foreign-registered or rental vehicles get no exemption, so complying with the test is always the better option.

There is no truly safe number, because blood alcohol depends on your weight, sex, metabolism, what you have eaten, and how fast you drink. As a very rough guide, the 0.05% (50mg%) limit is reached by many average-weight adults after about two to three standard drinks — roughly two to three 330ml beers at 5% over a couple of hours. The first drink alone can already put a lighter person near the line.

If you are subject to the 0.02% limit (under-20, provisional, or under-5-year licence), even one drink is likely to put you over. Because the calculation varies so much between people, the reliable approach is to use a BAC calculator to estimate your level, leave a wide safety margin, and if you have had anything to drink, take a Grab car, taxi, or tuk-tuk instead of driving.

An online BAC calculator uses the Widmark formula and its modern refinements to estimate your blood alcohol concentration from the inputs you provide — weight, sex, drink volume, alcohol strength, food intake, and time. It is a useful guide, but it is an estimate, not a measurement. Two people giving the same inputs can have noticeably different real BAC because of differences in metabolism, recent meals, medication, and liver function.

For driving in Thailand, treat the estimate conservatively. If a calculator shows you anywhere near the 0.05% limit (or 0.02% if you are a new driver), do not drive — the real value could be higher, and the only legally decisive reading is the police breathalyser at the roadside. The safest use of a calculator is to confirm you are well clear of the limit, or to check your morning-after risk before driving the next day.

Yes. Songkran (the Thai New Year water festival in April) and the December–January New Year period are Thailand's two deadliest stretches on the road, often called the "seven dangerous days". During these periods police set up far more roadside checkpoints, breath-test far more drivers, and enforcement is coordinated nationwide.

The legal limits do not change during the holidays — they are still 0.05% (and 0.02% for new drivers) — but your chance of being stopped and tested is much higher, and courts may take a stricter view. If you are travelling during Songkran or New Year, plan transport in advance: use Grab, taxis, songthaews, or stay where you are drinking. The combination of heavy traffic, festival drinking, and intensive enforcement makes driving after any alcohol a particularly bad idea at these times.

Thai law expresses the driving limit in milligram percent (mg%) — milligrams of alcohol per 100 millilitres of blood. The general limit of 50mg% is the same as 0.05% BAC or 0.5 ‰ (permille); the stricter new-driver limit of 20mg% equals 0.02% / 0.2 ‰. These are just different scales for the same thing: 50mg% = 0.05% = 0.5 g/L. Roadside breath tests measure alcohol in exhaled air in mg/L and convert to the blood figure.

A "standard drink" is an educational measure that lets you compare beer, wine, and spirits by alcohol content rather than volume. The WHO default of 10g of pure alcohol per drink is a sensible benchmark — roughly a 330ml beer at 5%, a 100ml glass of wine at 12%, or a 30ml shot at 40%. Counting standard drinks helps you estimate your BAC over an evening.

Thai police use officially approved and regularly calibrated breathalysers, which gives their readings legal weight in court. The devices carry a small built-in margin of error — typically a few percent on the displayed reading — and that tolerance is already factored into how they are certified for evidential use. Alcohol lingering in the mouth (from mouthwash, cough syrup, or a recent sip) can briefly raise readings, so officers normally allow a short wait before testing, and you can request a confirmatory blood test if you dispute the result.

Consumer-grade personal breathalysers are noticeably less accurate than police equipment, lose calibration over time, and have no legal standing in Thailand. They can be useful for awareness — particularly the morning after — but should never be your green light to drive. Online calculators don't measure anything; they model your BAC from the inputs you provide, so if your details are off, the estimate is off too.

On average, your body clears roughly one standard drink (10g of pure alcohol) per hour, or about 0.10–0.15 ‰ per hour — though body weight, sex, metabolism, food, and general health all shift the pace. As a rough guide, a 330ml beer or a single glass of wine can take 2–3 hours to fully clear; a heavier evening can run well into the next day.

To drive legally in Thailand you need to be back under 0.05% (or 0.02% if you are a new or young driver) — but the only fully safe target is zero. After a moderate evening of 3–4 drinks finishing around midnight, that realistically means waiting until the next morning, and adding a 1–2 hour buffer because clearance varies between people. If in doubt, don't drive: Thai police checkpoints operate at all hours, including early mornings.

Your body removes alcohol at a fairly steady rate — roughly 0.15 ‰ per hour, or about one standard drink per hour. Starting from a BAC of 1.0 ‰, it would take about 7–10 hours to clear completely; from 1.5 ‰, more like 12 hours. From a single beer at around 0.3 ‰, it takes roughly 2–3 hours to reach zero.

That figure is an estimate, not a guarantee. The actual time depends on your weight, sex, metabolism, whether you have eaten, and your general health, so two people who reach the same BAC can sober up at different speeds. Detection windows differ from "safe to drive" windows — alcohol can be detected in breath or blood for hours and in urine for longer — but the figure that matters for driving in Thailand is whether your blood concentration is back under the legal limit, and ideally at zero.

The morning after is one of the most common ways drivers end up over the limit. Your body clears alcohol at a steady, slow rate of roughly 0.1–0.15 ‰ per hour, and nothing speeds that up. If you finished the night around midnight at about 1.0 ‰, you can still be over the 0.05% limit well into the next morning — even after a full night's sleep, a hot shower, and a strong coffee. Sleep, caffeine, and a big breakfast may make you feel sharper than you are, but they do not lower your BAC.

Use the SmartBAC calculator to estimate roughly when your BAC should be back under the limit, then add a buffer of 2–3 hours because clearance varies between people — and remember new drivers must be under 0.02%, which takes longer. If you are anywhere near the limit, do not drive. Thai police checkpoints operate at all hours, including the early-morning rush.

The honest answer is that you cannot sober up faster. Your liver breaks down alcohol at an essentially fixed rate, and only time lowers your blood alcohol content. Popular "remedies" — black coffee, a cold shower, fresh air, exercise, a big meal after drinking, or being sick — do not change how quickly alcohol leaves your system.

What some of these can do is make you feel more alert, and that is precisely the danger: feeling more awake while your BAC is still above the limit can fool you into thinking you are fit to drive when you are not. Coffee, for example, masks tiredness without touching your alcohol level. Drinking water is sensible for rehydration and may ease a hangover, but it does not speed up sobering up. The only safe plan is to wait until your BAC is genuinely back down — or simply not drive that day.

Thailand does not have a single nationally-defined standard drink, so the international WHO standard of 10g of pure alcohol per drink is a sensible default — roughly the amount an average adult's body can process in one hour. To work out the standard drinks in any drink, multiply its volume in millilitres by its strength (ABV %) and by 0.79 (the density of ethanol), then divide by 10: (volume × ABV × 0.79) ÷ 10.

A 330ml beer at 5% ABV (a small Singha, Chang, or Leo) is about 1 standard drink, a 100ml glass of wine at 12% is 1 standard drink, and a 30ml shot of spirits at 40% is also 1 standard drink. A large 640ml bottle of Thai beer is closer to 2 standard drinks, and buckets or cocktails served at bars can contain several. Counting standard drinks helps you estimate your BAC over an evening.

Your liver does most of the work of breaking alcohol down, using enzymes to process it at a steady, limited rate. When you drink more than the liver can comfortably handle, the by-products of that process damage liver cells over time. This is why heavy or regular drinking is so closely linked to liver disease, and why alcohol is recognised worldwide as a leading cause of preventable death.

Alcohol-related liver damage usually develops in stages. The first is fatty liver disease (steatosis), where fat builds up in the organ — often with no symptoms and partly reversible if you stop drinking. Continued heavy drinking can lead to alcoholic hepatitis (inflammation) and eventually cirrhosis, where healthy tissue is permanently replaced by scarring. Cirrhosis cannot be reversed. WHO low-risk guidance suggests no more than 10 standard drinks per week with at least two alcohol-free days.

Sertraline is a widely used SSRI antidepressant, sold internationally under names such as Zoloft and Lustral. Standard medical guidance is that you can drink alcohol while taking sertraline, but it may make you feel drowsy, dizzy, or less alert. Because of this, it is often best to avoid alcohol for the first few weeks of treatment, until you can see how the medicine affects you.

There are good reasons for caution beyond drowsiness. Alcohol is itself a depressant, so it can worsen the low mood and anxiety the medication is prescribed to treat, and may blunt how well the treatment works. The combined sedative effect of alcohol and sertraline also makes driving especially risky. For advice tailored to your medicine and dose, speak to your doctor or pharmacist.