Blood Alcohol Calculator
Disclaimer: This is an estimate only. Actual BAC varies based on many factors including food intake, metabolism, medications, and tolerance. Never drink and drive.
About Blood Alcohol Calculator
What Is Blood Alcohol Content?
Blood Alcohol Content (BAC) measures the amount of alcohol in your bloodstream expressed as a percentage. A BAC of 0.08% means there are 0.08 grams of alcohol per 100 ml of blood. This is the legal driving limit in most US states. BAC determines the level of impairment: at 0.02% you feel relaxed, at 0.05% judgment and coordination begin to decline, at 0.08% motor control is significantly impaired, and at 0.15%+ there is severe impairment and risk of alcohol poisoning. Understanding your estimated BAC helps you make responsible decisions about driving and consumption.
The Widmark Formula
BAC is estimated using the Widmark formula: BAC = (Alcohol consumed in grams / (Body weight in grams x r)) - (0.015 x hours since drinking), where r is the gender constant (0.68 for men, 0.55 for women). The 0.015 represents the average metabolic elimination rate per hour. One standard drink contains approximately 14 grams of pure alcohol (12 oz beer at 5%, 5 oz wine at 12%, or 1.5 oz spirits at 40%).
How to Use This Calculator
Enter your body weight, gender, number of standard drinks consumed, and the time period over which you drank. The calculator estimates your current BAC, shows your impairment level, indicates whether you are above legal driving limits, and estimates how long until your BAC returns to zero. This is an estimate for educational purposes and should not be relied upon for legal decisions about driving.
Frequently Asked Questions
How long does it take to sober up?
Your body eliminates alcohol at approximately 0.015% BAC per hour. Nothing speeds this up: not coffee, food, water, or cold showers. If your BAC is 0.08%, it takes about 5.5 hours to return to zero.
Why do women reach higher BAC than men?
Women have a lower water content ratio (55% vs 68% in men), less alcohol dehydrogenase enzyme, and typically lower body weight. These factors combine to produce higher BAC from the same amount of alcohol.
Is this calculator accurate enough for legal purposes?
No. This provides an estimate based on average metabolic rates. Individual variation is significant. Never rely on any calculator to determine if you are safe to drive. When in doubt, do not drive.
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