Blood Alcohol Concentration (Widmark formula)

Theoretical blood alcohol concentration from consumed volume, body mass, sex, and time since drinking. For medical and forensic specialists.

How to use this calculator

Who this is for

Calculator for addiction specialists, toxicologists, emergency physicians, forensic medical experts, and law enforcement professionals. Used in acute ethanol poisoning, in-patient elimination forecasts, expert and investigative casework.

What the calculation shows

The Widmark formula (1932) gives a theoretical estimate of blood alcohol concentration from the volume consumed, body mass, sex, and time since drinking. It is a mathematical model. Actual concentration depends on ADH/ALDH activity, liver function, gastric contents, concurrent medications, and genotype. Individual variation reaches ±30 %.

Legal status

The result does not replace certified breathalyzer readings. The calculation has no evidentiary force in administrative or judicial proceedings, which rely only on certified instruments and laboratory blood ethanol measurement.

What this calculator does not do

This calculator is not for planning when it is safe to drive. A calculated zero result does not imply fitness to operate a vehicle. Cognitive and psychomotor impairment can persist for hours after ethanol clears. Only a certified breathalyzer gives an objective assessment. If there is any doubt about sobriety, do not drive.

About this calculator

Widmark's 1932 formula gives a theoretical BAC estimate. Actual concentration depends on ADH/ALDH activity, liver function, gastric contents, concurrent medications; individual variation reaches ±30 %. The calculation does not replace certified breathalyzer readings and has no evidentiary force in administrative or judicial proceedings.

Source

Widmark EMP. Die theoretischen Grundlagen und die praktische Verwendbarkeit der gerichtlich-medizinischen Alkoholbestimmung. Berlin: Urban & Schwarzenberg; 1932.

Formula version: widmark-1932-v1

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