Health
Blood Alcohol Calculator FAQ
Estimate BAC by weight and drink total, then see how the estimate fades over time.
FAQ
How is BAC estimated here?+
The calculator uses a Widmark-style formula that estimates your body water volume based on weight and sex, divides the total grams of alcohol consumed by that volume, then subtracts an average metabolic elimination rate multiplied by the hours elapsed since you started drinking. The result is a rough BAC percentage that trends downward over time.
Why is this estimate only?+
Real BAC varies significantly based on individual metabolism, how much food you have eaten, medications you are taking, your hydration level, overall health, and many other factors that this simple model cannot account for. Two people with the same weight and drink count can have very different actual BAC levels.
Does it support metric units?+
Yes. You can switch between imperial (pounds, fluid ounces) and metric (kilograms, milliliters) units using the toggle at the top of the calculator. All calculations adjust automatically to maintain accuracy.
Can I use this to decide if I can drive?+
No. This calculator provides a rough educational reference only and should never be used to determine fitness to drive or for any legal or medical purpose. Actual BAC depends on many individual factors that cannot be modeled here. Always err on the side of caution and arrange alternate transportation if you have been drinking.
What factors affect BAC beyond what this calculator shows?+
Food consumption slows alcohol absorption significantly, so a full stomach can produce a lower peak BAC than an empty one. Liver health, medications, fatigue, and carbonation in drinks can also affect how quickly alcohol enters and leaves your system. Genetic differences in metabolism enzymes cause wide variation between individuals.
How long does it take for BAC to return to zero?+
The average person metabolizes alcohol at a rate of about 0.015 BAC per hour, meaning it takes roughly one hour to eliminate one standard drink. However, this rate varies by individual, and higher BAC levels take proportionally longer to clear. Time is the only reliable way to reduce BAC — coffee, cold showers, and exercise do not speed up metabolism.
Does food or gender affect the BAC estimate?+
Yes. The Widmark formula accounts for sex through different distribution ratios (0.68 for men and 0.55 for women on average), which reflect differences in typical body water percentage. Food intake is not modeled here but can significantly reduce peak BAC by slowing alcohol absorption into the bloodstream.