What is the legal BAC limit?

In most US states, the legal limit for driving is 0.08%. Commercial drivers: 0.04%. Under 21: 0.00-0.02% (zero tolerance). Impairment begins well below 0.08%.

What counts as one standard drink?

One standard drink contains about 14 grams of alcohol: 12 oz beer (5%), 5 oz wine (12%), or 1.5 oz spirits (40%). Craft beers and cocktails often contain more.

How long does it take to sober up?

The body metabolizes alcohol at about 0.015% BAC per hour. There is no way to speed this up — coffee, food, and cold showers do not reduce BAC faster.

Why do women reach higher BAC?

Women typically have less body water and more body fat than men of the same weight. Since alcohol distributes in body water, women achieve higher BAC from the same amount of alcohol.

BAC Calculator

Estimate blood alcohol content based on drinks consumed, body weight, gender, and time elapsed.

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Standard Drinks

Weight

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Gender

Hours Since First Drink

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Body Fat % ?

Food Consumed

BAC Estimates

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Status & Safety

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Elimination Timeline

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How to Use This Calculator

Enter the number of standard drinks consumed, your weight, gender, and how many hours you have been drinking. The calculator estimates your current BAC, impairment level, and time until sober.

Formula

BAC = (Alcohol consumed in grams / (Body weight in grams × r)) × 100 - (0.015 × hours)

Where r = 0.68 for males, 0.55 for females. One standard drink = 14g alcohol. Metabolism rate = 0.015%/hour.

Example

Example: A 170 lb male, 3 drinks over 2 hours: BAC = (42 / (77110 × 0.68)) × 100 - 0.03 = 0.050% — some impairment, below legal limit.

Frequently Asked Questions

In most US states, the legal limit for driving is 0.08%. Commercial drivers: 0.04%. Under 21: 0.00-0.02% (zero tolerance). Impairment begins well below 0.08%.
One standard drink contains about 14 grams of alcohol: 12 oz beer (5%), 5 oz wine (12%), or 1.5 oz spirits (40%). Craft beers and cocktails often contain more.
The body metabolizes alcohol at about 0.015% BAC per hour. There is no way to speed this up — coffee, food, and cold showers do not reduce BAC faster.
Women typically have less body water and more body fat than men of the same weight. Since alcohol distributes in body water, women achieve higher BAC from the same amount of alcohol.

Related Calculators

Sources & References (5) ▾

Widmark EMP — Die theoretischen Grundlagen und die praktische Verwendbarkeit der gerichtlich-medizinischen Alkoholbestimmung (1932) — NIAAA (translated reprint)
NIAAA — Alcohol Use Disorder: A Comparison Between DSM-IV and DSM-5 (2012) — National Institute on Alcohol Abuse and Alcoholism
NHTSA — The Visual Detection of DWI Motorists (DOT HS 808 677, 1997) — NHTSA
Cederbaum AI — Alcohol metabolism. Clin Liver Dis. 2012;16(4):667-685 — Clinics in Liver Disease
CDC — Drunk Driving: Blood Alcohol Concentration (BAC) — CDC