BAC Calculator
Your curve, tuned to your body — not averages
The curve shows how alcohol builds up and fades in your blood — drink by drink, tuned to your weight, sex, and pace. You’ll see the peak, when it hits, and when you’re back to zero.
Blood alcohol content (BAC) measures the amount of alcohol in your bloodstream. Even moderate drinking affects reaction time, coordination, and decision-making. Use this calculator to get a quick estimate based on the Widmark formula — the same method used in forensic toxicology worldwide. For a more personalized result that accounts for your metabolism and food intake, try the AlcoBalance app.
This is an estimate only
This calculator provides a rough estimate based on the Widmark formula. Actual BAC depends on many factors including metabolism, food intake, medications, and individual physiology. Never drive or operate machinery based on a calculator estimate.
Want more accurate results?
The AlcoBalance alcohol monitoring app uses your personal profile and real-time metabolism modeling for up to 30% more accurate calculations.
Time to zero: when your curve hits 0.0
Run the numbers and you get more than a single reading. The calculator draws your whole curve and marks the moment you're back at 0.0. That time to zero is usually the real question anyway: not "how drunk am I now", but "when is this evening fully behind me".
The curve climbs while alcohol is still being absorbed, tops out at your peak, then fades at a steady rate: about 0.015% BAC (0.15 ‰) per hour for men, slightly less for women. That part you can't rush. Weight, sex and pacing set both your peak and your time to zero, which is why the result here is tuned to you and not to an average drinker.
How long alcohol stays in your system: the full breakdownHow accurate is this calculator?
Accurate enough to plan around, not to certify. Under the hood it runs the Widmark formula, the standard of forensic toxicology, extended with absorption over time and the strength of each drink. What you get is a realistic range instead of one idealized number.
Three things matter most: logging every drink honestly, getting the timing right, and your own elimination rate. The first two are in your hands right here. The third is why this is your curve and not a table of averages — and why the AlcoBalance app, which learns your profile, gets up to 30% closer still.
How the Widmark Formula Works
The Widmark formula, developed by Swedish chemist Erik Widmark in 1932, is the gold standard in forensic toxicology for estimating blood alcohol concentration. It calculates BAC using: BAC = (alcohol consumed in grams) / (body weight × distribution ratio) − (elimination rate × time). The distribution ratio (r) is 0.68 for males and 0.55 for females. The average elimination rate is 0.15‰ per hour.
Factors that affect your actual BAC include: body composition, food in stomach, hydration level, liver health, medications, and individual genetic variation in alcohol dehydrogenase enzyme activity.
Stages of Intoxication by BAC Level
The same dose affects everyone differently, but the overall picture by blood alcohol level looks like this:
Mild relaxation, attention drifts a little. From the outside nobody would notice.
Mood is up, you talk more, self-control drops. Reaction time is already slowing.
Coordination and speech slip. Reactions lag, and you overestimate what you can do.
Confusion, disorientation, possible memory gaps. High risk of injury.
Breathing and reflexes are suppressed. Risk of alcohol poisoning, which is a medical emergency.
How Long Until Alcohol Leaves Your System
Your liver clears alcohol at a nearly constant rate, about 0.15 ‰ per hour. Nothing speeds it up. Approximate time to full elimination for men:
| Drink | 60 kg | 80 kg | 100 kg |
|---|---|---|---|
| Beer, 500 ml (5%) | ≈ 3 h | ≈ 2 h | ≈ 1.5 h |
| Glass of wine, 150 ml (12%) | ≈ 2 h | ≈ 1.5 h | ≈ 1 h |
| Bottle of wine, 750 ml (12%) | ≈ 10.5 h | ≈ 8 h | ≈ 6.5 h |
For women, elimination takes roughly 20–25% longer, because the distribution ratio is lower. Actual time depends on metabolism, food, and liver health. Treat these numbers as an optimistic estimate.
Full elimination table and test detection windowsFrequently Asked Questions
What is permille (‰) and how does it relate to BAC percent?
Permille means one thousandth. A blood alcohol level of 0.5 ‰ equals 0.5 grams of pure alcohol per liter of blood. The US and UK write the same value as a percentage: 0.05% BAC = 0.5 ‰.
How long until alcohol is fully eliminated?
The liver processes about 0.15 ‰ per hour, roughly one standard drink. A 500 ml beer clears in about 2–4 hours, a bottle of wine in 6–15 hours depending on weight and sex. Details are in the table above.
What BAC does one beer produce?
A 500 ml beer at 5% contains about 20 g of pure alcohol. By this calculator's model, that peaks at roughly 0.2 ‰ for an 80 kg man and around 0.4 ‰ for a 60 kg woman, 40–50 minutes after drinking. Classic Widmark tables say 0.35–0.6 ‰. They assume every gram hits your blood at once and ignore what your body eliminates while it's still absorbing.
Can you speed up alcohol elimination?
No. Coffee, a cold shower, a walk, or greasy food don't make your liver work faster. It clears alcohol at a constant rate. Coffee makes you feel more alert, but your BAC stays the same. The only thing that works is time.
How accurate is an online BAC calculator?
The Widmark formula gives an estimate with an error of up to 20–30%: it ignores food, medications, hydration, and individual metabolism. Don't use it for decisions where that error matters, like whether to drive. The AlcoBalance app builds your curve from your profile and the session you're in right now, so the estimate lands closer to reality.
What is the legal BAC limit for driving?
In the US the limit is 0.08% BAC (Utah: 0.05%). The UK allows 80 mg per 100 ml of blood, roughly 0.08%, but Scotland is stricter at 0.05%. Australia draws the line at 0.05, with zero tolerance for learner and provisional drivers. In Canada 0.08 is the criminal threshold, though most provinces add penalties from 0.05. Limits change, so check your local rules. And reaction time suffers well below any of them: if you've been drinking, don't drive.
How many drinks is .08 for a 200-pound man?
By this calculator's model, a 200-pound man reaches about 0.08% BAC after five standard beers back to back, or roughly six spread over two hours. Textbook math says four. That count ignores everything your body eliminates while you're still drinking. Food, pace and body composition shift it further, so treat the number as a range rather than a rule and run your own inputs above.
How many drinks is .17 BAC?
Around nine to ten standard drinks over an evening for an average-sized man. Lighter bodies and female physiology get there noticeably sooner. At 0.17% BAC (1.7 ‰) most people are deep in the confusion stage: memory gaps, poor balance, a real risk of blackout. If your curve is pointing that way, the exact count matters less than stopping the climb.