FAQ | Japan Drink Driving Limit, Penalties & BAC Rules

Japan's drink-driving threshold is 0.15mg of alcohol per litre of breath (about 0.03% blood alcohol, or 0.3‰). Test at or above this and you commit 酒気帯び運転 (alcohol-affected driving), which is split into two bands. 0.15–0.25 mg/L: 13 demerit points and a 90-day licence suspension. 0.25 mg/L or more: 25 points and licence revocation (a 2-year disqualification). Both carry a criminal penalty of up to 3 years in prison or a fine of up to ¥500,000.

Even below that reading, if alcohol leaves you "unable to drive normally" you commit the more serious 酒酔い運転 (drunk driving) regardless of the number — 35 points, licence revocation (3-year disqualification), and up to 5 years in prison or a ¥1,000,000 fine. The threshold is only the line for punishment: if you are driving, the safe amount of alcohol is zero.

The criminal penalty for 酒気帯び (alcohol-affected) driving is up to 3 years in prison or a fine of up to ¥500,000. On top of that come administrative penalties: 13 demerit points (90-day suspension) at 0.15–0.25 mg/L of breath, and 25 points with licence revocation (a 2-year disqualification) at 0.25 mg/L or more.

The more serious 酒酔い (drunk) driving carries up to 5 years in prison or a ¥1,000,000 fine, 35 demerit points and licence revocation (a 3-year disqualification). Where injury or death is caused, dangerous-driving or negligent-driving charges can be added, leading to a long custodial sentence. Police prosecute on the spot — there is no verbal warning.

The key difference is whether there is a numerical threshold. 酒気帯び運転 (alcohol-affected driving) is judged by the number — a breath reading of 0.15 mg/L or more. It is made out by the alcohol level alone, so you are in breach even if you feel completely sober.

酒酔い運転 (drunk driving), by contrast, is judged not by a number but by whether alcohol has left you "unable to drive normally". An officer assesses it from signs such as being unable to stand straight or speak clearly, and it can apply even with a low breath reading. The penalty is far heavier: 35 demerit points, licence revocation (3-year disqualification), and up to 5 years in prison or a ¥1,000,000 fine.

The demerit points for drink driving are heavy, and a single offence brings a serious penalty. Alcohol-affected driving at 0.15–0.25 mg/L of breath is 13 points — a 90-day suspension if you have no prior record. Alcohol-affected driving at 0.25 mg/L or more is 25 points, which means instant licence revocation (a 2-year disqualification).

Drunk driving (酒酔い) is 35 points, bringing licence revocation with a 3-year disqualification. With a prior record or where an accident is involved, the disqualification period is extended further. Even 13 points means a 90-day suspension, so "just a little" still has an outsized impact on your licence.

Even a first offence with no prior record is punished strictly. Alcohol-affected driving at 0.15–0.25 mg/L is 13 points and a 90-day licence suspension; 0.25 mg/L or more is 25 points and licence revocation (2-year disqualification). After arrest, the criminal process (summary indictment, fine, etc.) and the administrative licence penalty proceed separately.

Where property damage is involved, or where it is judged to be drunk driving (35 points), revocation follows even for a first offence. The suspension or revocation notice arrives later, with an opportunity to attend and give your account. Because handling varies by case, check the specifics with a lawyer or your prefectural police.

Yes. In Japan it is not only the driver — the people around them can also be prosecuted. Whoever provided the vehicle (lent the car knowing the person would drink and drive) faces the same penalty as the driver: up to 5 years in prison or ¥1,000,000 for drunk driving, or up to 3 years or ¥500,000 for alcohol-affected driving.

Whoever served the alcohol (knowing the person would drive) and any passenger (who rode along knowing the driver had been drinking) are also punished — up to 3 years in prison or ¥500,000 for drunk driving, and up to 2 years or ¥300,000 for alcohol-affected driving. The law expects you not to serve, not to ride along, and not to let others drive.

No. Refusing a breath test requested by a police officer is itself an offence under the Road Traffic Act, punishable by up to 3 months in prison or a fine of up to ¥500,000. Refusing does not let you avoid a penalty — it only makes your position worse.

Police run checkpoints frequently at night, around nightlife districts, and over the New Year period. If you dispute the result you can ask for confirmation by a blood test, but only after taking the test in the first place. Complying is always the better choice.

There is no single answer, because blood alcohol depends on your weight, sex, metabolism, what you have eaten, and how fast you drink. Japan's threshold of 0.15 mg/L of breath (≈0.03%) is very low — as a rough guide, even a 500ml beer (one medium bottle) or one gō of sake can put some people over.

Smaller people, and anyone drinking on an empty stomach, go over on even less. Because individual variation is so large, the reliable approach is to use a BAC calculator to estimate your level and clearing time, leave a wide margin, and if you have had anything at all to drink, take a taxi or a 代行 (daikō) driver service 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 different real BAC because of differences in metabolism, recent meals, medication, and liver function.

For driving in Japan, treat the estimate conservatively. If a calculator shows you anywhere near the threshold, 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. A revision of the Road Traffic Act that took effect on 1 November 2024 made alcohol-affected cycling (自転車の酒気帯び運転) a punishable offence. The threshold is exactly the same as for cars — 0.15mg of alcohol per litre of breath (about 0.3mg/mL in blood). Riding a bicycle over that level can bring up to 3 years in prison or a fine of up to ¥500,000.

And if you ride while "unable to ride normally" because of alcohol (drunk cycling, 酒酔い), the heavier penalty applies: up to 5 years in prison or a ¥1,000,000 fine. "It's only a bicycle" is no longer a defence. If you have had anything to drink, don't ride — push the bike or take another way home.

Bicycle drink driving does not carry demerit points (the 13/25-point system) the way cars do, because the points system applies to vehicles that require a driving licence. However, in serious cases a rider can be treated as a "person posing a danger" under Article 103 of the Road Traffic Act, and the prefectural public safety commission can suspend (up to 180 days) or revoke their car driving licence — a separate route from points.

From 1 April 2026, a "blue ticket" (fixed-penalty) system will also apply to bicycles, but serious violations such as alcohol-affected and drunk cycling are excluded — they continue to be handled as criminal matters (fine or imprisonment). Bicycle drink driving is not something a small fixed penalty settles.

Yes. The 2024 revision extended third-party liability to bicycles too. Whoever provided the bicycle knowing the person would ride after drinking faces the same penalty as the rider — up to 3 years in prison or ¥500,000. Whoever served the alcohol, or a passenger who rode along knowing the rider was over the limit, faces up to 2 years or ¥300,000.

A "bicycle" here includes the electrically power-assisted bicycle (電動アシスト自転車), which counts as a bicycle in law and follows the same rules and penalties. Note that an electric kick-scooter (特定小型原付) is treated as a moped, not a bicycle — but its drink-driving threshold (0.15 mg/L of breath) and penalties match those for cars, so riding one after drinking is equally prohibited.

Japan's Road Traffic Act sets the drink-driving threshold in milligrams of alcohol per litre of breath (mg/L). The threshold of 0.15 mg/L corresponds to about 0.03% blood alcohol, or 0.3‰ (permille). These are just different scales for the same thing, and police roadside tests measure the alcohol in your exhaled breath in mg/L.

A "standard unit" lets you compare beer, wine, and spirits by alcohol content rather than volume. In Japan, 20g of pure alcohol counts as one unit — roughly a 500ml beer at 5%, 180ml of sake (1 gō), a 200ml glass of wine at 12%, or a 60ml double whisky at 40%. Counting units helps you estimate your level over an evening.

Japanese police use certified, regularly calibrated breath alcohol detectors, which gives their readings legal weight in court. The devices carry a small built-in margin of error, and that tolerance is already factored into how they are certified for evidential use. Alcohol lingering in the mouth (from a recent drink or mouthwash) can briefly raise readings, so officers normally allow a short wait before testing.

Consumer-grade personal alcohol checkers are less accurate than police equipment, lose calibration over time, and have no legal standing. 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 7g of pure alcohol per hour (about 0.1–0.15 ‰ per hour). Since one Japanese unit is 20g of pure alcohol, a single unit takes about 3–4 hours to clear — though body weight, sex, metabolism, food, and general health all shift the pace.

To drive in Japan you need to be back under 0.15 mg/L of breath, but the only fully safe target is zero. After a moderate evening of 3–4 drinks finishing late, 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: checkpoints operate at all hours, including the early morning.

Your body removes alcohol at a fairly steady rate — roughly 0.15 ‰ per hour, or about 7g of pure alcohol an 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 ‰, allow roughly 3–4 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 — what matters for driving in Japan 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 0.15 mg/L threshold 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. If you are anywhere near the limit, do not drive. Japanese 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.

In Japan, 20g of pure alcohol is commonly counted as "one unit" (per the Ministry of Health). This is roughly the amount an average adult's body can process in a few hours. To work out the pure alcohol in any drink, use volume (ml) × ABV (%) × 0.8 ÷ 100.

As a guide, a 500ml beer at 5%, 180ml of sake (1 gō, ~15%), a 200ml glass of wine at 12%, and a 60ml double whisky at 40% are each about one unit (20g of pure alcohol). A strong canned chū-hai can be close to 2 units in a single can. Counting units helps you estimate your level over an evening and how long it takes to clear.

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, 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. Japan's MHLW suggests keeping "moderate" drinking to about 20g of pure alcohol a day.

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.