Blood Alcohol Content (Widmark) Calculator

About this calculator

This calculator applies the Widmark formula, BAC = (A / (W × r)) − (β × H), where A is grams of alcohol consumed, W is body weight, r is the Widmark factor accounting for body water distribution (roughly 0.68 for men and 0.55 for women), β is the average elimination rate (about 0.015% per hour), and H is hours since drinking began. The Widmark factor is why the same number of drinks typically produces a higher BAC in someone with less body water.

Alcohol educators and researchers use it to illustrate roughly how BAC rises and falls over an evening, but it's an estimate only — genetics, food intake, medications and the formula's population averages all cause real BAC to vary, so it should never be used to decide whether it's safe to drive.