BAC Calculator
Estimate blood alcohol content with the Widmark formula.
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1 standard drink = 12 oz beer (5%) = 5 oz wine (12%) = 1.5 oz spirits (40%)
Disclaimer: This is a rough estimate for educational purposes only. Actual BAC varies based on metabolism, food intake, medications, and other factors. Never use this to determine if you are safe to drive.
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Frequently Asked Questions
What is the Widmark formula? +
The Widmark formula estimates BAC as: (alcohol consumed in grams) / (body weight in grams x r) - (0.015 x hours). The "r" factor is 0.68 for males and 0.55 for females, accounting for differences in body water content.
What counts as one standard drink? +
One standard drink contains about 14 grams (0.6 oz) of pure alcohol. That equals roughly 12 oz of regular beer (5%), 5 oz of wine (12%), or 1.5 oz of distilled spirits (40%).
How long does it take for BAC to reach zero? +
The body metabolizes alcohol at roughly 0.015% BAC per hour, regardless of body size. So a BAC of 0.08% takes about 5.3 hours to fully metabolize. Coffee, food, and water do not speed this up.
Why does body weight affect BAC? +
Alcohol distributes through body water. Heavier people generally have more body water to dilute the alcohol, resulting in a lower BAC from the same number of drinks compared to lighter individuals.
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