BAC Calculator

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🍺 Beer 330ml

🍻 Pint 568ml

🍷 Wine 175ml

🍷 Large Wine 250ml

🥃 Spirit 25ml

🍸 Cocktail

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Hours since first drink

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Standard Drinks

Sober In (approx)

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⚠️ Important Safety Warning
I am not a doctor or medical professional. This calculator provides estimates only based on the Widmark formula. Actual BAC depends on many factors including metabolism, medications, liver function, and tolerance. NEVER use this to decide if you are safe to drive. If you have consumed ANY alcohol, do not drive. Call a taxi, use a designated driver, or use public transport.

BAC Over Time

See how your estimated BAC changes hour by hour as your body metabolises alcohol. Calculate your BAC first, then this timeline will populate.

Calculate your BAC first to see the timeline

Legal BAC Limits by Country

Drink-driving limits vary significantly around the world. Some countries have zero tolerance.

Country	BAC Limit

BAC Effects Guide

Common Myths

How Blood Alcohol Content Works

Blood Alcohol Content (BAC) measures the percentage of alcohol in your bloodstream. A BAC of 0.08% means 0.08 grams of alcohol per 100 millilitres of blood. Even small amounts of alcohol affect your brain, judgement, and reaction time.

What Affects Your BAC?

Body weight — Heavier people generally have a lower BAC from the same amount of alcohol because there is more body water to dilute it.
Biological sex — Women typically reach higher BAC levels than men of the same weight because of differences in body water percentage and metabolism enzymes.
Rate of consumption — Drinking quickly raises BAC faster than your liver can process it. The liver metabolises roughly one standard drink per hour.
Food in your stomach — Eating before or while drinking slows alcohol absorption, resulting in a lower peak BAC. An empty stomach means faster absorption.
Type of drink — Carbonated drinks (sparkling wine, mixers with fizz) can speed up alcohol absorption. Higher-concentration drinks are absorbed differently to lower-concentration ones.
Medications — Many common medications interact with alcohol, amplifying its effects or slowing metabolism. Always check with your pharmacist.

How Your Body Processes Alcohol

When you drink, alcohol is absorbed through the stomach lining (about 20%) and small intestine (about 80%) into the bloodstream. Your liver does most of the work breaking it down using an enzyme called alcohol dehydrogenase (ADH), processing roughly 0.015% BAC per hour — equivalent to about one standard drink.

Nothing speeds this process up. Coffee, cold showers, exercise, and fresh air might make you feel more alert, but your BAC stays the same until your liver has done its job. The only thing that lowers BAC is time.

What Is a “Standard Drink”?

Standard drink sizes vary by country, which is a common source of confusion:

UK: 8g of pure alcohol (roughly a small glass of wine or half a pint of normal-strength beer)
USA: 14g of pure alcohol (a 12oz beer at 5%, 5oz wine, or 1.5oz spirit)
Australia: 10g of pure alcohol
Europe (varies): 10-12g depending on country

This means “one drink” in the US contains nearly twice the alcohol of “one unit” in the UK. Always check what standard your country uses when interpreting health guidelines.

International Drink-Driving Limits

Legal blood alcohol limits for driving vary dramatically around the world. Some countries operate a zero-tolerance policy, while others allow up to 0.08% BAC. If you’re travelling abroad, knowing the local limit could save you from serious legal consequences.

Zero Tolerance Countries (0.00% BAC)

These countries do not permit any alcohol in the blood while driving:

Brazil, Czech Republic, Hungary, Morocco, Saudi Arabia, UAE, Qatar, Kuwait, Oman, Pakistan, Bangladesh, Nepal, Paraguay, Romania, Slovakia, Uruguay

In many of these countries, penalties are severe — including immediate licence suspension, heavy fines, and imprisonment even for first offences.

Very Low Limits (0.02-0.03% BAC)

Effectively zero after even one drink:

Sweden (0.02%), Norway (0.02%), Poland (0.02%), Estonia (0.02%), China (0.02%), Japan (0.03%), India (0.03%), Russia (0.035%)

Moderate Limits (0.05% BAC)

The most common limit worldwide — roughly one drink for most people:

Australia, Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Netherlands, Portugal, Scotland (UK), South Africa, Spain, Switzerland, Thailand, Turkey

Higher Limits (0.08% BAC)

A handful of countries still allow 0.08%:

England & Wales (UK), USA (most states), Canada, Mexico, Malaysia, Singapore

Note: England & Wales have one of the highest limits in Europe at 0.08%, while Scotland lowered theirs to 0.05% in 2014. There have been repeated calls to bring the rest of the UK in line.

Special Rules to Watch For

New/young drivers: Many countries (Germany, Italy, Australia, etc.) have lower or zero-tolerance limits for drivers under 21 or within their first few years of holding a licence.
Commercial drivers: Professional/HGV drivers usually face stricter limits (often 0.02-0.04%) everywhere.
Morning after: A common trap for travellers — you may still be over the limit from the previous evening. In countries with very low limits, even 6-8 hours after moderate drinking can be risky.
Roadside penalties: Some countries (France, for example) previously required drivers to carry breathalysers in their vehicle, though enforcement varies.

Alcohol & Health: What the Science Says

Understanding how alcohol affects your body goes beyond just BAC numbers. Here are the key health facts backed by current research.

Short-Term Effects by BAC Level

0.01-0.03% — Slight mood elevation, mild relaxation. Most people feel “normal” but reaction times are already measurably slower.
0.04-0.06% — Lowered inhibitions, warmth, relaxation. Minor impairment in reasoning and memory. This is the “buzzed” stage.
0.07-0.09% — Impaired balance, speech, vision, reaction time, and hearing. Judgement significantly affected. Legally impaired in most countries.
0.10-0.15% — Significant impairment of motor control. Slurred speech, poor coordination, blurred vision. Very high risk of accidents.
0.16-0.30% — Severe impairment. Nausea, disorientation, need for assistance walking. Memory blackouts likely.
0.30%+ — Risk of unconsciousness, respiratory depression, and death. This is a medical emergency — call 999/112/911 immediately.

Long-Term Health Risks

The UK Chief Medical Officers’ guideline recommends no more than 14 units per week, spread over 3 or more days. Regular heavy drinking increases the risk of liver disease, heart disease, stroke, several types of cancer (particularly breast, mouth, throat, and liver), mental health problems, and weakened immune function.

Alcohol and Sleep

While alcohol can make you fall asleep faster, it significantly disrupts sleep quality. It reduces REM sleep (the restorative stage), increases nighttime awakenings, and worsens sleep apnoea. You may sleep for 8 hours after drinking but wake feeling unrefreshed.

Alcohol and Medication

Mixing alcohol with medication is more common and more dangerous than most people realise. Antibiotics, painkillers (especially paracetamol and ibuprofen), antidepressants, blood pressure medication, and antihistamines can all interact with alcohol. Always read the patient information leaflet or ask your pharmacist.

UK Drink-Drive Limit: Why England Still Hasn’t Changed

England, Wales, and Northern Ireland remain at 0.08% BAC — one of the highest limits in Europe. Scotland lowered to 0.05% in 2014, and road safety campaigners continue to call for the rest of the UK to follow. The government has so far resisted, citing enforcement priorities over limit changes. However, with most of Europe at 0.05% or lower, the UK is increasingly an outlier.

13 May 2026

Holiday Driving: Know Before You Go

With summer approaching, millions of UK drivers will be taking their cars to Europe. France, Spain, Italy, Greece, and Portugal all have a 0.05% limit — significantly lower than what many British drivers are used to. A single large glass of wine could put you over the limit in these countries. The penalty in France for a first offence is a €135 fine; in Spain it can be up to €1,000.