Estimate blood alcohol content (BAC) using the Widmark formula. This is an educational estimate only — actual BAC varies by individual, and you should never drive after drinking regardless of the result.
This tool estimates Blood Alcohol Concentration (BAC) based on factors including number of drinks consumed, body weight, sex, and time elapsed since drinking began. It's intended as a rough educational estimate only, not a precise or legal measurement of actual impairment.
This calculator typically uses the Widmark formula: BAC = (Alcohol consumed in grams ÷ (Body weight in grams × distribution ratio)) × 100 − (Metabolism rate × Hours elapsed). The distribution ratio differs between men (~0.68) and women (~0.55) due to average differences in body water content.
Enter your weight, sex, number and type of drinks consumed, and time elapsed, and the calculator provides an estimated BAC value.
Example: A person weighing 70 kg who consumes 2 standard drinks within an hour might show an estimated BAC in the range associated with mild impairment, though individual results vary significantly.
Is this calculator accurate enough to determine if I'm safe to drive? No — this tool provides only a rough estimate. Actual BAC is affected by many individual factors (metabolism, food intake, medications, health conditions) that a formula can't fully capture, so it should never be used to decide whether it's safe to drive.
What factors affect BAC besides the ones in this calculator? Food consumption, hydration, medications, liver function, and even genetics can all significantly influence how alcohol is absorbed and metabolized, beyond what a simple formula accounts for.
Why do men and women have different BAC calculations for the same amount of alcohol? On average, women tend to have a lower percentage of body water relative to body weight than men, which means alcohol becomes more concentrated in their bloodstream for the same amount consumed and body weight.
How does the body eliminate alcohol? The liver metabolizes alcohol at a relatively constant rate (roughly one standard drink per hour for many people), which is why BAC gradually decreases over time after drinking stops.
What should I do if I'm unsure whether I'm safe to drive? The safest choice is to never drive after drinking any amount of alcohol — use a designated driver, rideshare, or public transport instead of relying on any BAC estimate.