BAC Calculator — Blood Alcohol Content Estimator

The body eliminates alcohol at roughly 0.015% BAC per hour — a near-fixed rate that coffee, cold showers, and exercise do not change. From a peak of 0.08%, that's about 5 hours to reach zero. Breath and saliva tests typically detect alcohol for 12–24 hours; standard urine tests for up to 80 hours (depending on test type); and hair tests for up to 90 days.

The CDC defines a US standard drink as 14 grams of pure ethanol — equivalent to 12 oz of beer at 5% ABV, 5 oz of wine at 12% ABV, or 1.5 oz of 80-proof liquor (40% ABV). Many craft beers, IPAs, and cocktails contain 1.5–3 standard drinks worth of alcohol despite looking like a single drink.

Food in the stomach slows alcohol absorption — peak BAC after drinking on a full stomach is roughly 30% lower than the same drinks on an empty stomach. Food does not reduce the total alcohol absorbed, only the peak; the total area under the BAC curve is similar. The Widmark formula does not account for food.

In all 50 US states, the limit is 0.08% for drivers age 21 and older. For commercial drivers, the limit is 0.04%. For drivers under 21, most states use 0.02% or zero tolerance. Utah dropped its general limit to 0.05% in 2018. A driver can still be charged with DUI below the limit if impairment is observed.

The most accurate method is a blood draw, used in fatal-crash investigations. Police roadside tests use a breath analyzer that estimates blood BAC from breath alcohol — accurate within about ±0.01% when calibrated and used correctly. Personal breathalyzers and calculators like this one are educational tools, not legally admissible measurements.