Estimate your blood alcohol concentration (BAC) using the Widmark formula. Enter your sex, weight, drinks and time drinking to see estimated BAC and time until sober.
Choose your unit system, then enter your sex, weight in kg (metric) or pounds (imperial), the number of standard drinks and how long you've been drinking. The calculator applies the Widmark formula to estimate your BAC and how long until you're sober.
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A blood alcohol calculator estimates your BAC from the number of standard drinks, your weight and sex, and how long you've been drinking, using the Widmark formula. It's a rough guide — never use it to decide whether to drive.
BAC (‰) = (drinks × 12) ÷ (r × weight) − 0.15 × hours
r is the distribution factor (men ~0.68, women ~0.55). The body eliminates about 0.15‰ per hour. 1‰ = 0.1%.
It's a rough estimate. Real BAC depends on metabolism, food, medication, fatigue and drink strength. Only a breathalyser or blood test is reliable — never rely on this for driving decisions.
About 12 g of pure alcohol — roughly a small shot of spirits, a small glass of wine or half a pint of regular beer. Strong pours and large glasses contain more than one standard drink.