BAC Calculator
Estimate blood alcohol content (BAC) from standard drinks consumed, body weight, sex and time using the Widmark formula.
Severe Impairment
At 1.954%, you're estimated to be at or above the legal driving limit in most U.S. states (0.08%) — do not drive.
This is a rough estimate for education only — actual BAC is affected by food, medications, and individual metabolism. Never use this to decide whether it's safe to drive.
About the BAC Calculator
This calculator estimates blood alcohol content using the Widmark formula, which combines standard drinks consumed, body weight, sex and time elapsed into a rough BAC percentage. It's a population-average formula, not a breathalyzer reading — food in your stomach, medications, liver function, and how quickly you actually drank can all push your real BAC meaningfully above or below what the math predicts.
People generally reach for a BAC estimate out of curiosity or for general alcohol-education purposes, understanding roughly how different amounts of drinking and time affect the numbers behind terms like "legally intoxicated."
This is an educational estimate only, not a measurement of your actual impairment, and it should never be used to decide whether it's safe to drive or operate anything — if there's any doubt, don't drive. Nothing you enter is stored or sent anywhere; it's calculated locally in your browser.
How it’s calculated
The Widmark formula estimates BAC from grams of alcohol consumed, body weight, a sex-based distribution constant (r), and time elapsed: BAC ≈ (alcohol grams × 5.14) / (weight in lb × r) − (0.015 × hours). The r constant — roughly 0.68 for men and 0.55 for women — reflects that alcohol distributes through body water, and men typically have a higher proportion of body water relative to weight than women, so the same amount of alcohol tends to produce a lower BAC in a man of equal weight.
The 0.015-per-hour term subtracts a standard average elimination rate, since the body metabolizes alcohol at a roughly steady pace over time — though this rate, too, varies by individual, which is one more reason the result is an estimate rather than a precise reading.
Frequently asked questions
What BAC level is considered legally intoxicated?
In most U.S. states, 0.08% is the legal limit for driving, though commercial drivers and drivers under 21 face lower limits in many places. Impairment to reaction time and judgment can begin well below that threshold, though.
How long does it take to sober up?
The body eliminates alcohol at roughly 0.015% BAC per hour on average, so a BAC of 0.08% would take around five to six hours to reach zero under that average rate — though individual metabolism can make this faster or slower.
Does eating food affect BAC?
Yes — food in your stomach slows alcohol absorption into the bloodstream, which can lower peak BAC compared to drinking on an empty stomach, though the Widmark formula used here doesn't factor in food intake at all.
Why do men and women get different BAC estimates for the same drinks?
The Widmark formula uses a different distribution constant by sex because alcohol dissolves in body water, and men on average have a higher proportion of body water relative to total weight, which tends to dilute the same amount of alcohol more for a man than for a woman of equal weight.
Can this calculator tell me if I'm okay to drive?
No — it's an educational estimate, not a measurement of your actual impairment or a legal determination. No calculator can reliably tell you it's safe to drive after drinking; if you've had any alcohol, the safest choice is not to drive.
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