BAC Calculator
Enter your sex, weight, the number of standard drinks and the hours since you started to estimate your blood alcohol content.
Drinking Details
Estimated blood alcohol content from drinks, body weight, sex and elapsed time using the Widmark equation, with time-to-zero.
Formula
BAC% = (drinks × 14 g ÷ (r × weight(kg) × 1000)) × 100 − 0.015 × hours, with r = 0.68 (male) or 0.55 (female).
Reference Values
- •US standard drink = 14 g alcohol
- •Elimination ≈ 0.015%/hour
- •Most EU limits 0.05%; 0.08% in parts of the US
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FAQ
Common questions about BAC Calculator
How we calculate this
We use the standard published formula for this calculation, and we show the working so you can check it.
Spotted a mistake? Tell us and we'll check it within a few days. See how we check our calculators.
Medical disclaimer
This tool gives a general estimate for information only. It is not medical advice and cannot diagnose a condition. Talk to a doctor, midwife or other qualified professional about your own situation.
Alcohol warning
Never drive after drinking. Blood alcohol varies with food, medication, health and many other factors. This estimate can be wrong, and the legal limit depends on where you are.