BAC Calculator (Blood Alcohol Content)
Estimate Blood Alcohol Content from drinks using the Widmark formula. See US legal driving thresholds and hours until BAC reaches 0.00.
HEALTHEstimate Blood Alcohol Content (BAC) from drinks consumed using the Widmark formula. See US legal driving thresholds (0.08% for adults 21+, 0.04% for commercial drivers, 0.02% for under 21) and hours until BAC reaches 0.00.
Widmark formula: BAC% = (alcohol_grams / (body_weight_grams × distribution_ratio)) × 100 - (0.015 × hours). Distribution ratio is 0.68 for males, 0.55 for females. One US standard drink = 14g pure alcohol (12 oz 5% beer, 5 oz 12% wine, 1.5 oz 40% spirits). Your liver clears about 0.015 BAC per hour - food, coffee, and cold showers do not speed this up.
BAC Calculator (Blood Alcohol Content)
Estimate your Blood Alcohol Content (BAC) from drinks consumed using the Widmark formula. See US legal driving thresholds and hours until you reach 0.00.
How BAC Is Calculated
The Widmark formula estimates Blood Alcohol Content from alcohol consumed, body weight, sex, and time. BAC (%) = (alcohol_grams / (body_weight_grams × distribution_ratio)) × 100 − (0.015 × hours). The distribution ratio is 0.68 for males and 0.55 for females because females have less total body water on average.
One US standard drink contains 14 grams of pure alcohol. That is 12 oz of 5% beer, 5 oz of 12% wine, or 1.5 oz of 40% spirits. Cocktails and craft beers often contain 1.5 to 3 standard drinks each. Always measure pours - "one drink" at home is rarely actually one drink.
US legal limits: 0.08% BAC for drivers 21+, 0.04% for commercial drivers, and 0.02% (or zero tolerance) for drivers under 21. Utah lowered to 0.05% in 2018. Impairment starts well below 0.08%: judgment and reaction time degrade noticeably starting around 0.02%, and 0.05% is enough to substantially raise crash risk.
Estimate only. Actual BAC varies by metabolism, food intake, hydration, medications, and many other factors. Never drive after drinking - even a "legal" BAC impairs judgment. Use a ride service, designated driver, or wait it out.