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:

• Blood alcohol concentration
• Patient's weight
• Patient's gender
• Time since consumption of the alcohol

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 × 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:

1. Forrest ARW. The estimation of Widmark's factor. J Forensic Sci Soc. 1986:26:249-52.
2. Watson PE, Watson ID, Batt RD. Prediction of blood alcohol in human subjects. Updating the Widmark equation. J Stud Alcohol 1981;42:547-56.
3. Widmark EMP. Principles and Applications of Medicolegal Alcohol Determination. Davis, CA. Biomedical Publications. 1981, pp. 107-8.
4. Simon HK, Cox JM, Sucov A, et al. Serum ethanol clearance in intoxicated children and adolescents presenting to the ED. Acad Emerg Med. 1994;1(6):520-4.
5. Brennan DF, Betzelos S, Reed R, et al. Ethanol elimination rates in an ED population. Am J Emerg Med. 1995;13(3):276-80.
6. Gershman H, Steeper J. Rate of clearance of ethanol from the blood of intoxicated patients in the emergency department. J Emerg Med. 1991;9(5):307-11.
7. Smith GD, Shaw LJ, Maini PK, et al. Mathematical modelling of ethanol metabolism in normal subjects and chronic alcohol misusers. Alcohol & Alcoholism. 1993;28( l): 25-32.