BAC Calculator.
Estimate blood alcohol content using the Widmark formula. Enter weight, sex, drinks consumed, and time since first drink.
1 standard drink = 12 oz beer (5%), 5 oz wine (12%), or 1.5 oz spirits (40%)
Estimated BAC
Effect
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The Widmark Formula
Developed by Swedish pharmacologist Erik Widmark in the 1930s, the Widmark formula is the standard method used by toxicologists, law enforcement, and medical professionals worldwide to estimate BAC from known variables.
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Understanding BAC: Widmark Formula and Alcohol Metabolism Methodology.
The Calculation Branch
Industrial Standards.
The 0.015% per hour elimination rate is an average — individual rates range from 0.010 to 0.030 depending on liver enzyme activity, body composition, food intake, hydration, and medications. This means actual BAC could be higher or lower than the estimate by 20–30%. The Widmark formula also doesn't account for alcohol absorption rate, which is slower on a full stomach.
In-Depth Analysis & Reference Data
A 'standard drink' varies by country. The US standard is 14g of pure alcohol (12 oz 5% beer, 5 oz 12% wine, 1.5 oz 40% spirits). The UK unit is 8g, Australia uses 10g. When comparing BAC calculators, ensure they use the same drink definition. Bar drinks often exceed one standard drink — a cocktail with 2 oz of spirits counts as 1.33 standard US drinks; a pint of craft beer at 8% counts as 1.6 standard drinks.
Registry Questions & FAQ.
Does food affect BAC?
Yes, significantly. Food slows alcohol absorption from the stomach into the bloodstream. Drinking on a full stomach can delay peak BAC by 30–90 minutes and reduce peak BAC by up to 30% compared to drinking on an empty stomach. However, food does not change how quickly your body eliminates alcohol — total alcohol processed over a night remains the same; food just smooths out the curve and reduces the peak.
What BAC levels cause different effects?
0.01–0.03%: Subtle relaxation, no clear impairment for most. 0.04–0.07%: Mild euphoria, reduced reaction time, some coordination issues. 0.08–0.10%: Legal limit for driving in the US — clear impairment in coordination, judgment, and memory. 0.15–0.25%: Severe impairment, possible blackout. 0.25%+: Life-threatening — respiratory depression risk. 0.40%+: Potentially fatal for most people.
Estimates for planning. Always confirm against an authoritative source.