BAC Calculator
Estimate your blood alcohol content based on the Widmark formula
Blood alcohol content (BAC) measures the amount of alcohol in your bloodstream. Even moderate drinking affects reaction time, coordination, and decision-making. Use this calculator to get a quick estimate based on the Widmark formula — the same method used in forensic toxicology worldwide. For a more personalized result that accounts for your metabolism and food intake, try the AlcoBalance app.
1 standard drink = 14g pure alcohol (355ml beer, 150ml wine, 44ml spirits)
This is an estimate only
This calculator provides a rough estimate based on the Widmark formula. Actual BAC depends on many factors including metabolism, food intake, medications, and individual physiology. Never drive or operate machinery based on a calculator estimate.
Want more accurate results?
AlcoBalance app uses your personal profile and real-time metabolism modeling for up to 30% more accurate calculations.
How the Widmark Formula Works
The Widmark formula, developed by Swedish chemist Erik Widmark in 1932, is the gold standard in forensic toxicology for estimating blood alcohol concentration. It calculates BAC using: BAC = (alcohol consumed in grams) / (body weight × distribution ratio) − (elimination rate × time). The distribution ratio (r) is 0.68 for males and 0.55 for females. The average elimination rate is 0.15‰ per hour.
Factors that affect your actual BAC include: body composition, food in stomach, hydration level, liver health, medications, and individual genetic variation in alcohol dehydrogenase enzyme activity.