Have you ever wondered how to calculate or at least estimate your blood alcohol concentration, or BAC, after having a few drinks with your friends? How can you do it if you don’t have a breathalyzer with you ?.

Well, here is the formula to estimate your BAC. It is called the Widmark Fomula.

**BAC = [Alcohol consumed in grams / (Body weight in grams x r)] x 100**

“r” is the gender constant and is equal to 0.55 for a woman and 0.68 for a man

But how do you know how much alcohol you consumed?

Well, that is easy.

**Alcohol consumed in grams = Volume in mL * % of alcohol in the beverage * 0.789 g/mL**

Let’s do an example.

You are a man. (r = 0.68)

Your weight is 80 Kg = 80’000 g

You drank 3 cans (3*375 mL) of beer (4% = 0.04) while watching soccer.

What is your BAC?

3*375 mL* 0.04 * 0.789 g/mL / (80’000 g * 0.68) * 100 = **0.06 **

What if you drink a whole bottle of 700 mL Vodka (45% = 0.45)

700 mL* 0.45 * 0.789 g/mL / (80’000 g * 0.68) * 100 = **0.4****6**

In case you use** imperial units,** you can easily convert :

1 fl. Oz = 29.6 mL

1 pound = 454 g

If you’re not much for math, you can also use one of the numerous websites that help you find out your BAC.

For example:

http://www.rupissed.com/index.html