Your BAC on the impairment scale
The amber/red boundary is the 0.08% legal driving limit. The pointer is your estimate.
This is a rough estimate only. Many factors affect real BAC. Never drive after drinking, regardless of this result.
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BAC Calculator
Estimate your blood alcohol content from the number of drinks, your body weight, sex, and how long you have been drinking, using the Widmark formula.
Estimated BAC
0.05%
Impairment begins
US legal driving limit0.08%
Time until sober—
Status—
How it works
The Widmark formula estimates blood alcohol content from the grams of alcohol consumed, your body mass, a distribution ratio that differs by sex, and the alcohol your liver clears over time (about 0.015% per hour).
BAC% = (alcohol grams ÷ (weight g × r)) × 100 − 0.015 × hours
r = 0.68 (male) or 0.55 (female)
r = 0.68 (male) or 0.55 (female)
Because it ignores food, drinking pace, medications, and individual metabolism, real BAC can be higher or lower than this estimate.
Frequently asked questions
Can I use this to decide if I can drive?
No. This is an educational estimate with a wide margin of error. The only safe amount of alcohol before driving is none.
Why do men and women get different results?
Body water distribution differs on average, so the same alcohol produces a higher concentration in a smaller water volume. The formula reflects this with different distribution ratios.