| Blood alcohol concentration | |
| unit | mg/dL mmol |
| Patient's weight | |
| unit | Kg lbs |
| Patient's gender | Male Female |
| Time since consumption of the alcohol (hr) | |
This calculation estimates the amount of alcohol consumed in mL based on the blood alcohol concentration (BAC) in mg/dL or mmol/L, for a single ingestion of alcohol (at one time) and the time since the alcohol was consumed.
The following parameters must be entered:
This calculator is based on a modification of the Widmark equation, which was published by a Swedish physician EMP Widmark in 1932. One modification of this equation is an average metabolism of ethanol of 20-30 mg/dL/hr (4.3-6.5 mmol/L/hr).
There are separate equations for male and female as the volume of distribution differs by gender.
Based upon % Ethanol:
[Males] Alcohol consumption = (BAC*body weight)/(1.22* % ethanol)
[Females] Alcohol consumption = (BAC * body weight)/(1.51*%Ethanol)
Based upon Proof:
[Males] Alcohol consumption = (BAC* body weight)/(0.61* proof)
[Females] Alcohol consumption = (BAC * body weight)/(0.75*proof)
Where BAC is the blood alcohol concentration in mg/dL, weight is the body weight in kg.
Time factor:
Added to this is 20 mg/dL/hr x hrs since ethanol is consumed.
Notes
Multiple modifications of this formula have occurred over time; each with their advantages and disadvantages and inaccuracies
In chronic alcoholics; the metabolism of ethanol may occur at up to 30 mg/dL/hr and thus, the amount of alcohol consumed may be higher than predicted here for a chronic alcoholic (due to only 20 mg/dL/hr being subtracted).
References:
Forrest ARW. The estimation of Widmark's factor, J. For Sci Soc. 1986;26: 249-52.
Watson PE, Watson ID, Batt RD. Prediction of blood alcohol in human subjects. Updating the Widmark equation. Journal of Studies on Alcohol 1981; 42: 547-56.
Widmark EMP. Principles and Applications of Medicolegal Alcohol Determination. Davis, CA. Biomedical Publications. 1981, pp. 107-8.