How much blood alcohol does a glass of wine have?

Wine itself does not have a per mille. It contains alcohol, which is expressed in percent by volume (vol.-%). (For details, see the question "What percentage of alcohol does wine contain?")

In per mille (‰), the concentration of alcohol in human blood is indicated after the consumption of alcoholic beverages. Here, a Blood alcohol concentration (BAK) of 1 ‰ means that 1 kilogram of blood contains 1 gram of pure alcohol.

The blood alcohol concentration can be calculated using the so-called Widmark formula. The decisive factors are body weight and the proportion of body fluid, which is different for men and women; for men it is about 68 percent, for women about 55 percent.

It is also important to know the alcohol content and the amount of the drink consumed. A glass of wine is usually 0.2 litres (200 ml), and an alcohol content of 13 percent by volume can be assumed as a guideline for a dry wine.

Calculating the alcohol value

This alcohol content must first be converted from percent by volume to grams of pure alcohol. This is done using the following equation (g = gram, ml = millilitre):

Alcohol content [in g] = amount of liquid [in ml] x (vol.% / 100) x 0.8

If we insert the corresponding values (200 ml and 13 vol.-%) here, the result is: 200 x (13 / 100) x 0.8 = 20.8 g

This results in a content of 20.8 g of pure alcohol for a glass of the representative example wine.

Calculation of the per mille value

This alcohol value as well as the information on body weight and body fluid content can then be used in the Widmark formula for BAC calculation. This uses the above-mentioned standard values for the body fluid percentage for men and women, given as decimal numbers (68% = 0.68; 55% = 0.55):

BAC [‰] = alcohol [g] / ( body weight [kg] x body fluid percentage )

For a man with a body weight of 70 kilograms, this results in a BAC value of about 0.44 per mille after drinking a glass of wine, for a woman of the same weight a BAC value of about 0.54 per mille:
20.8 g / (70 kg x 0.68) = 0.44 ‰
20.8 g / (70 kg x 0.55) = 0.54 ‰

The per mille value for a glass of wine increases the higher its alcohol content and decreases the higher the body weight.

For an exact calculation of the BAC value, the so-called resorption deficit must also be taken into account, because the alcohol intake of the body (resorption) also depends on the drinking speed and the contents of the stomach. Furthermore, the body continuously breaks down alcohol (about 0.1 to 0.2 per mille per hour).

Basically, the strong recommendation is: anyone who has drunk alcohol (even if it is only a glass of wine) should no longer drive a vehicle - neither a car (let alone a truck or bus) nor a motorbike or bicycle. According to German law, a relative inability to drive can already exist from 0.3 per mille, from 0.5 per mille driving a vehicle is in any case punishable as an administrative offence, and from 1.1 per mille absolute inability to drive is present. Therefore: Don't drink and drive!