Blood Alcohol (BAC) Calculator

Estimate blood alcohol concentration from drinks, weight and time.

Estimated BAC

0.046%

Below the 0.08% US limit — but any alcohol impairs driving

Alcohol consumed: 42grams
Hours to fully sober: 3hours

Estimated BAC0.046%

This is an educational estimate, not medical advice. Talk to a healthcare professional about your situation.

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Quick answer

3 drinks over 2 hours for a 180 lb man estimates a BAC around 0.045%; for a 140 lb woman, about 0.075%.

How it works

The Widmark formula estimates BAC from alcohol consumed, body weight and a sex-based distribution factor, minus about 0.015% per hour of metabolism. It's a rough estimate — food, medications and individual metabolism all change the real number.

Formula

BAC = (drinks × 14 g) ÷ (weight g × r) × 100 − 0.015 × hours

Assumptions & limitations

Results are rounded for display.

Frequently asked questions

What's a standard drink?

12 oz of 5% beer, 5 oz of 12% wine, or 1.5 oz of 40% spirits — each contains about 14 grams of alcohol.

Can I drive under 0.08%?

Impairment begins well below 0.08%, and some places have lower limits. The only safe BAC for driving is zero.