BAC Calculator - Blood Alcohol Content

Blood alcohol content, often shortened to BAC, describes the amount of alcohol circulating in the bloodstream. A BAC of 0.080% means that alcohol accounts for approximately 0.08 grams per 100 milliliters of blood. This calculator provides a mathematical estimate based on the Widmark formula. It is useful for understanding how drink count, alcohol dose, body weight, biological distribution, and time can influence an estimate, but it is not a breath test, blood test, or legal measurement. The calculation first multiplies the number of drinks by the grams of pure alcohol in each drink. In many countries a standard drink contains about 14 grams, although official definitions and serving sizes vary. That alcohol amount is divided by body weight in grams and a distribution ratio. This calculator uses 0.68 for male and 0.55 for female, common educational approximations reflecting average differences in body-water distribution. The quotient is converted to a percentage, then 0.015 percentage points are subtracted for every elapsed hour to represent average metabolism. Actual absorption and elimination differ substantially among people. Food, drinking speed, medication, health conditions, age, body composition, serving size, beverage strength, and individual metabolism can all change the result. Alcohol may also continue to enter the bloodstream after the final drink, so a calculated value can fall while a person's measured BAC is still rising. The fixed elimination rate used here is an average rather than a promise about any individual. Use the alcohol-per-drink field to model the beverage rather than assuming every glass, can, or cocktail is one standard drink. Pure alcohol grams can be estimated from beverage volume, alcohol by volume, and ethanol density. Mixed drinks and generous pours commonly contain more than one standard serving. Accurate input improves the mathematical estimate, but it cannot remove biological uncertainty. No BAC estimate should be used to decide whether to drive, operate equipment, supervise others, or perform another safety-sensitive task. Legal limits vary by location, driver status, and age, and impairment begins before many statutory limits. The safest approach after drinking is to use a sober driver or another form of transportation. Seek urgent medical help for confusion, repeated vomiting, slow or irregular breathing, seizures, inability to wake, or other signs of alcohol poisoning.