Blood Alcohol Calculator

A free blood-alcohol content (BAC) calculator using the classic Widmark equation. Accounts for sex, body mass, stomach state and up to 12 drinks at arbitrary ABV. Shows peak promille, full elimination time and the moment you fall under the legal limit in Russia (0.16 ‰), Europe (0.5 ‰) and the United States (0.8 ‰).

How to use

1
Enter parameters

Weight in kilograms, sex, drinking start time and stomach state.

2
Add drinks

Pick a type (preset ABV/volume auto-fills) or set % and ml manually.

3
Read the result

Peak promille, peak time, full sober time and when you may drive in six jurisdictions.

Estimate your BAC and when it is legal to drive

0.00 ‰
Add drinks to estimate BAC
0 g
Pure alcohol
—
Peak at
—
Fully sober
—
May drive at
BAC over time
Legal driving limit by country Tap a country to use its limit
⚠ Estimate only. Widmark estimate has ±20 % spread. Not legal evidence. Real BAC depends on genetics, medication, hydration, temperature and activity. Never drive after drinking — even a calculated 0.00 ‰ does not guarantee sobriety.

Features

Widmark equation Multiple drinks Stomach state When can I drive Elimination curve Works offline

FAQ

How accurate is this calculator?

The Widmark formula has ±20 % spread — real BAC depends on genetics, metabolic rate, medication, hydration, temperature and activity. For legal purposes always rely on official breath/blood testing.

What does promille mean?

Promille (‰) is parts per thousand. 1 ‰ = 1 gram of pure alcohol per 1 litre of blood = 0.1 % BAC. The US legal limit is 0.08 % = 0.8 ‰.

Why different values for men and women?

The Widmark r factor reflects body water fraction: ~0.68 for men, ~0.55 for women. Same dose, same body mass — a woman ends up with higher BAC.

What does "stomach state" mean?

Food slows alcohol absorption: empty → peak at 30 min, full meal → peak at 1.5 h. Elimination rate (0.15 ‰/h) is unaffected.

Can I rely on this to decide to drive?

No. Treat the result as a coarse estimate and add a 1–2 hour safety margin. Never drive after drinking, even when the calculator reads 0.00 ‰.

💡 Want us to improve this tool just for you?

We can — and it's free! Just send us a quick message with your idea. If you'd like to discuss it in detail, leave your email and we'll get back to you. You can stay anonymous.

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Who is this tool for?
🧘 Wellness & Meditation
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