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Blood Alcohol Calculator

Calculate your blood alcohol concentration based on the Widmark formula.

BAC rangeEffect
0.0 ‰No impairment
0.1–0.3 ‰Slight disinhibition, feeling of warmth
0.3–0.5 ‰Reduced reaction time, elevated mood
0.5–1.1 ‰Noticeable impairment of coordination and reaction time
1.1–2.0 ‰Severe balance issues, slurred speech
> 2.0 ‰Impaired consciousness, life-threatening

How it works

This calculator uses the Widmark formula: Alcohol (g) = Volume × (ABV / 100) × 0.8. BAC = Alcohol (g) / (Body weight × r), where r = 0.68 (men) or 0.55 (women). Elimination rate is approximately 0.15‰ per hour. This is an estimate — individual factors may vary.

Frequently Asked Questions

How is BAC calculated?+
Using the Widmark formula: alcohol (g) / (body weight × r). r = 0.68 for men, 0.55 for women. This estimate is medically established but varies individually.
How fast does the body metabolize alcohol?+
About 0.015–0.02 % per hour, on average 0.015 % BAC. Metabolism cannot be sped up by coffee, water, or exercise.
What are the legal BAC limits?+
Most U.S. states: 0.08 % BAC. Many European countries: 0.05 %. Germany: 0.05 %. New drivers and under 21: typically 0.00 %. Always check local law.
Why is the estimate imprecise?+
Individual factors like stomach contents, liver function, sex, medications, and body composition can shift the real value by ±20–30 %.
Are women more sensitive to alcohol?+
Yes. Women on average have lower body water and reduced alcohol dehydrogenase activity. For the same intake, BAC is higher.
When is it safe to drive again?+
Only at 0.00 % BAC. After reaching 0.10 %, full clearance takes about 6–7 hours. Residual alcohol the next morning is common — even after 8 hours of sleep.

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