Work out blood alcohol content instantly with clear inputs, formula shown and shareable results.
This is the Widmark equation: BAC = alcohol grams / (body water ratio x body weight in grams), expressed as a percentage, less 0.015 percentage points per hour of elimination. Elimination is nearly constant at about 0.015% an hour regardless of how much was drunk, which is why time is the only thing that lowers BAC.
Widmark equation
BAC % = alcohol grams / (r x weight in grams) x 100, with r = 0.68 male or 0.55 female
Elimination
current BAC = peak BAC - 0.015 x hours elapsed
BAC % = alcohol grams / (r x weight in grams) x 100, with r = 0.68 male or 0.55 female. This is the Widmark equation: BAC = alcohol grams / (body water ratio x body weight in grams), expressed as a percentage, less 0.015 percentage points per hour of elimination.
Elimination is nearly constant at about 0.015% an hour regardless of how much was drunk, which is why time is the only thing that lowers BAC.
Enter body weight, sex, pure alcohol consumed, hours since the first drink. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.