BAC Calculator
Estimate your blood alcohol content using the Widmark formula.
1 drink = 1.5oz 80-proof liquor, 12oz 5% beer, or 5oz 12% wine (all ≈14g alcohol)
Estimated BAC
0.042%
Mild Impairment
BAC Scale
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Tips for responsible drinking and staying safe.
Frequently Asked Questions
What is the Widmark formula for BAC?
BAC = (alcohol consumed in grams / (body weight in grams × r)) × 100 − (0.015 × hours elapsed). r is the Widmark factor: 0.68 for males, 0.55 for females. A standard drink contains 14g of pure alcohol.
What BAC is the legal limit for driving in the US?
In all 50 US states, the legal BAC limit for driving is 0.08% for adults 21 and over. Commercial drivers have a limit of 0.04%, and drivers under 21 face zero-tolerance laws (0.00–0.02% depending on the state).
How long does it take for alcohol to leave your system?
The average person metabolizes alcohol at approximately 0.015% BAC per hour. No method reliably speeds this up — coffee, food, and water only address symptoms, not actual BAC.