Blood Alcohol Content (BAC) Calculator — Free Online
Estimate your BAC using the Widmark formula. Enter your weight, gender, number of drinks, and hours spent drinking. Shows estimated BAC, time to sober, and legal limit status. 100% private, no sign-up.
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Estimated BAC
0.000%
Time to Sober
0 hours
Legal Limit Status (0.08%)
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This calculator provides estimates only. Never rely on it to determine if you are safe to drive. When in doubt, do not drive.
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Frequently Asked Questions
BAC is the percentage of alcohol in your bloodstream. A BAC of 0.08% means 0.08 grams of alcohol per 100 milliliters of blood. In most countries, 0.08% is the legal limit for driving.
The Widmark formula calculates BAC as: BAC = (Alcohol in grams / (Body weight in grams x Widmark ratio)) x 100 - (Elimination rate x hours). The ratio is 0.68 for men and 0.55 for women.
The body eliminates alcohol at about 0.015% BAC per hour. It takes roughly one hour to process one standard drink. Coffee and cold showers do not speed up elimination — only time works.
This calculator provides estimates based on the Widmark formula. Actual BAC varies by metabolism, food intake, medications, and health conditions. Never rely solely on a calculator to determine if you are safe to drive.
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Last updated: June 2026