Blood Alcohol Content (BAC) Calculator

About this calculator

This calculator estimates blood alcohol content in per mille using the Widmark formula, which combines total alcohol consumed with body weight, a sex-specific body water distribution constant, and the time elapsed since drinking began (since the liver metabolizes alcohol at a roughly constant rate over time). Because men and women distribute alcohol differently through body water, the same weight and drink count produce different estimated BAC for each.

People use it to get a rough sense of impairment level after drinking — for context against legal driving limits, which vary by country but are commonly around 0.5 per mille — or to estimate how long it will take for the level to drop to a safer point. It is explicitly an estimate: individual metabolism, food intake, medication and other factors all shift the real number, so it should never be treated as a precise measurement or used to decide whether it's actually safe to drive.