Used Formulas

We used the formulars from Widmark and Watson — with the modification by Eicker (for the female blood alcohol content) — to calcualte the blood alcohol content and alcohol degradation in this module.

Variables and Constants

pa = Density of alcohol (g/ml) = 0.8

pb = Density of blood (g/ml) = 1.055

w = Parts water in blood (%) = 0.8

v = Volume of the drink (ml)

e = Alcohol concentration in the drink (^v/_v)

t = Age (in years)

h = Height (in cm)

m = Weight (in kg)

Widmark-Formel

Blood Alcohol Concentration (BAC) => c

c = A / (m * r)

Mass of alcohol intake (in gramm) => A

A = V * e * pa

Factor for alcohol degradation “Reduktionsfaktor” (by sex) => r

• male: r = 0,7
• female: r = 0,6

Watson-Addition

Reduktionsfaktor => r

r = (pb * kw) / (w * m)

Water in the body (by sex) => kw

• male kw = 2,447 - (0,09516 * t) + (0,1074 * h) + (0,3362 * m)
• female kw = 0,203 - (0,07 * t)    + (0,1069 * h) + (0,2466 * m)

Combined

c = (pa * v * e * w) / (pb * kw)

Final Formel

• male: (pa * v * e * w) / (pb * (2,447 - (0,09516 * t) + (0,1074 * h) + (0,3362 * m)))
• female: (pa * v * e * w) / (pb * (0,203 - (0,07 * t)    + (0,1069 * h) + (0,2466 * m)))

Alcohol degradation

Average is 0.15 g/kg per hour (0.0025 per minute).