Blood Alcohol Calculator
Estimate using the Widmark formula. Educational only. Never use this to decide if you can drive — always err on the side of "no."
Estimated BAC
Right now
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Legal limit (US driving)
0.08%
Status
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Impairment level
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Hours until 0.00%
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This is an estimate. Period.
Real BAC depends on dozens of factors this calculator can't see: food in stomach, exact alcohol absorption rate, medications, fatigue, individual liver enzyme genetics, hydration, and how recently you ate. Your actual BAC can be ±30% from this number.
The legal limit for driving in most US states is 0.08%. Utah is 0.05%. Many countries are lower or zero. Commercial drivers and underage drivers have stricter limits.
The math (Widmark, 1932)
Distribution ratio: 0.68 for men, 0.55 for women (women have proportionally less body water on average, so the same drinks produce higher BAC). The 0.015%/hour subtraction is the average ethanol metabolism rate — your liver clears alcohol at this approximate steady pace.
Plan for zero
If there's any chance you'll need to drive, drink water and stop early. Better: have a plan that doesn't involve driving at all (rideshare, designated driver, public transit). The downside of "I think I'm fine" is unforgivable; the downside of "I called an Uber" is twelve dollars.
Estimate — not medical advice
Never use this to decide whether it is safe to drive. Blood alcohol estimates vary enormously between people, and this cannot account for your metabolism, what you ate, medications, fatigue, or how long ago you drank. The only safe rule after drinking is not to drive.
This is an estimate, not medical advice, and not a diagnosis. It doesn't know your history, your medications, or your other results, and it should never be used to start, stop, or change treatment. If a number here concerns you, take it to a doctor or pharmacist rather than acting on it.