Blood Alcohol Content (BAC) Calculator

Blood Alcohol Content (BAC) is the percentage of alcohol in your bloodstream — the same measurement used by police breathalyzers and legal BAC limits worldwide. A BAC of 0.08% means there are 0.08 grams of ethanol per 100 milliliters of blood. Our calculator estimates this value using the Widmark equation, published by Swedish scientist Erik Widmark in 1932 and still used today by forensic toxicologists and clinical researchers.

Enter your body weight, biological sex, and each drink you consume (with a timestamp), and the calculator will compute your rising and falling BAC on a live chart. It also estimates when your BAC will reach 0.00% based on the average ethanol elimination rate of roughly 0.015% per hour that has been established across decades of controlled pharmacokinetic studies.

Everything runs in your browser. Your weight, sex, and drink log never leave your device — we do not send this data to any server, and no account is required.