MayoCalc / Health

BAC Calculator

Estimate your blood alcohol content based on drinks, weight, and time.

Last updated April 2026
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1 standard drink = 14g of pure alcohol. Select your drink type above for accurate results.
Estimated BAC
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Time to 0.00%
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Time to 0.08%
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Disclaimer: This tool is for general educational and informational purposes only. It does not constitute medical advice, professional diagnosis, or treatment and is not a substitute for consultation with a qualified healthcare provider. No doctor-patient relationship is created by your use of this tool. Results are estimates based on published formulas and population-level data that may not reflect your individual medical circumstances. Neither MayoCalc nor Cook Media Systems assumes any liability or responsibility for damage or injury (including death) to any person arising from the use of any information, results, or content provided by this tool. Always consult your physician or other qualified healthcare provider with any questions about a medical condition. See our full Disclaimer and Terms of Service.

How BAC Is Estimated

Blood Alcohol Concentration (BAC) is estimated using the Widmark formula, which accounts for the amount of alcohol consumed, body weight, biological sex (affecting water content), and time elapsed. One standard drink contains approximately 14 grams of pure alcohol: a 12 oz beer (5% ABV), a 5 oz glass of wine (12% ABV), or a 1.5 oz shot of spirits (40% ABV). The body metabolizes alcohol at an average rate of approximately 0.015% BAC per hour.

BAC = (Alcohol in grams / (Body Weight in grams x Widmark r)) - (0.015 x Hours)
Widmark r: 0.68 for men, 0.55 for women

How to Use This Calculator

Enter the number and type of drinks consumed, your weight, sex, and the time period over which you drank. The calculator estimates your current BAC, the time until your BAC reaches 0.00%, and the time until you reach the legal driving limit (0.08% in most U.S. states). This is an estimate only and should not be used to determine fitness to drive.

The Alcohol Calorie Calculator shows the caloric impact of each drink type.

BAC Levels and Effects

0.02-0.03%: Relaxation, slight mood elevation. 0.05-0.06%: Lowered inhibitions, impaired judgment. 0.08%: Legal intoxication in most states; significant impairment of motor skills and reaction time. 0.10-0.12%: Clear deterioration of coordination and speech. 0.15%+: Major impairment of balance and movement. 0.30%+: Risk of loss of consciousness. 0.40%+: Risk of death from respiratory failure.

BAC Calculator FAQ

Why does body weight affect BAC?
Alcohol distributes through body water. A larger person has more body water to dilute the alcohol, resulting in a lower BAC from the same amount of alcohol. This is also why biological sex matters: women typically have a higher body fat percentage and lower body water percentage than men of the same weight, resulting in higher BAC from the same number of drinks.
Can I speed up alcohol metabolism?
No. Coffee, cold showers, food, and exercise do not speed up alcohol metabolism. The liver processes alcohol at a roughly fixed rate of about one standard drink per hour. The only thing that lowers BAC is time. Food consumed before or during drinking can slow absorption (peak BAC is lower), but it does not speed up elimination.

How Blood Alcohol Content Works

Blood Alcohol Content (BAC) measures the percentage of alcohol in your bloodstream by weight. A BAC of 0.08% (the legal driving limit in all 50 U.S. states) means 0.08 grams of alcohol per 100 milliliters of blood. BAC is influenced by several factors: the amount of alcohol consumed, the time period over which drinks were consumed, body weight (larger bodies dilute alcohol more), biological sex (women generally reach higher BAC than men at the same consumption level due to differences in body water percentage and alcohol dehydrogenase enzyme levels), food intake, and individual metabolism.

The Widmark formula, developed by Swedish scientist Erik Widmark in the 1930s, remains the standard BAC estimation method. It calculates BAC based on alcohol consumed (in grams), body weight, a gender-specific distribution ratio (0.68 for men, 0.55 for women), and an elimination rate of approximately 0.015% per hour. This calculator uses the Widmark equation with standard drink equivalents: one standard drink equals 14 grams of pure alcohol (12 oz of 5% beer, 5 oz of 12% wine, or 1.5 oz of 40% spirits).

BAC Levels and Impairment

Impairment begins well below the legal limit. At 0.02% BAC, judgment and relaxation increase. At 0.05%, coordination and reaction time decline measurably. At 0.08%, muscle coordination, balance, reasoning, and self-control are significantly impaired. At 0.15%, major loss of balance and vomiting are common. BAC above 0.30% carries risk of loss of consciousness, and levels above 0.40% can be fatal. The liver metabolizes alcohol at a relatively fixed rate (approximately one standard drink per hour), and no method (coffee, cold showers, exercise) accelerates this process. The Hydration Calculator can help plan water intake alongside alcohol consumption.

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