AtlasCalc❤️ HealthbeginnerOffline
Blood Alcohol (BAC)
Estimated blood alcohol concentration using Widmark's formula.
Inputs
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Result
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Enter values and press Calculate — the result appears here.
How it works
The formula behind this calculator.
BAC% = (alcohol_g / (weight_kg × r)) × 100 − 0.015 × hours
- alcohol_g
- Grams of pure ethanol consumed
- weight_kg
- Body weight in kg
- r
- Body-water constant (0.68 men, 0.55 women)
- hours
- Time since first drink
Widmark's formula accounts for body water and a ~0.015%/hr elimination rate. Real BAC also depends on food, liver function, and medications.
Example: Three 12-oz beers (56 g) over 2 hours for an 80-kg man → ~0.05%
Ref: Widmark (1932)
Tips
- 💡 Widmark's formula is an estimate. Real BAC depends on liver function, food intake, medications, and hydration.
- 💡 Never drive after drinking — even small amounts of alcohol impair reaction time.