How much blood alcohol do I have?

You can calculate your blood alcohol concentration yourself using the Watson formula. First, you need to determine the pure alcohol of your drink, and then you can determine the approximate alcohol level you have.

To calculate the pure alcohol, you simply have to multiply the size of your drink by the Vol-%/ 100 and multiply this value by 0.8. This will give you the grams of pure alcohol you are consuming when you drink the beverage. Here are a few examples:

  • In a half liter of beer with 5 per mille there are 500 ml x (5/100) x 0.8 = 20 grams of pure alcohol.

  • In a 0.2 l wine glass with 11% there are 200 ml x (11/100) x 0.8 = 17.6 grams of pure alcohol.

  • In a shot glass (4 cl) of 40% vodka, there are 40 ml x (40/100) x 0.8 = 12.8 grams of pure alcohol.

If you know the pure alcohol content of your drink, you can deduce your alcohol level from it. To do this, simply divide the pure alcohol content by your body fluid in kg. The body fluid is about 60% for women and 70% for men.

So if a woman weighs 60 kg and drinks a standard glass of wine (0.1 l), her alcohol level is: 10 g/ (60 x 0.6) = 0.28 per mille.

A 75 kg man, after the same consumption, has a value of 10g/ (75 x 0.7) = 0.19 per mille.

The blood alcohol concentration decreases by 0.1 to 0.2 per mille per hour, primarily because the liver breaks down the alcohol. The woman from the example is therefore back at zero after 1.5 - 3 hours, the man after 1 - 2 hours. By the way, the breakdown of alcohol cannot be accelerated - neither by soft drinks nor by fresh air, walking or dancing.

If the calculations sound too complicated for you, you can easily calculate your blood alcohol level with an online alcohol calculator, e.g.
this one. It will tell you how much alcohol you have and when you're expected to be sober again. This can help you decide which mode of transportation should be your means of choice.


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