Blood Alcohol Calculator
Free BAC calculator to estimate your blood alcohol content and understand impairment levels.
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Last updated: January 2026
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Frequently Asked Questions
What is blood alcohol content (BAC)?
BAC is the percentage of alcohol in your bloodstream. A BAC of 0.08% means 0.08 grams of alcohol per 100 mL of blood. Most countries set 0.08% as the legal driving limit.
How long does it take for alcohol to leave my system?
Your body metabolizes alcohol at about 0.015% BAC per hour. At 0.08% BAC, it takes roughly 5-6 hours to reach 0.00%. Factors like weight, gender, and liver health affect this rate.
Why does body weight affect BAC?
Larger bodies have more blood and water to dilute alcohol. A 180 lb person drinking 3 beers will have lower BAC than a 120 lb person drinking the same amount.
Why do women generally have higher BAC than men?
Women typically have higher body fat percentage and less body water than men. Since alcohol dissolves in water, women have less fluid to dilute it, resulting in higher BAC from the same amount.
What counts as one standard drink?
One standard drink contains about 14 grams of pure alcohol: 12 oz beer (5%), 5 oz wine (12%), or 1.5 oz liquor (40%). Craft beers and cocktails often contain more alcohol.