Blood alcohol content is a measure of the percentage of alcohol present in the blood, after someone has consumed alcoholic beverages. There are two important mathematical measures involved in what results as the BAC.
Beginning with the amount of alcohol contained in different types of beverages, one can of beer (12 ounces) contains 5% alcohol by volume. This translates to 0.6 ounces of alcohol per can. With the lowest concentration of alcohol, ounce per ounce, many people mistakenly believe they can consume large quantities of beer without equaling harder liquor.
However, wine is not that far off with 12% alcohol by volume. A typical 5oz (ounce) glass contains the same 0.6oz of alcohol that a 12oz beer has. Thus, one can drink 2.4 times the amount of beer as wine, and get the same amount of alcohol.
Hard liquor, as in 80-proof, is a different story. Usually consumed in shot glasses, 80-proof liquor contains the same 0.6oz of alcohol as one glass of wine or one can of beer.
Thus 1.5oz of liquor = 5oz. of wine = 12oz. of beer.
The second set of mathematics involved in the percentage of alcohol in the blood is related to the person’s total volume of blood. BAC cannot give a total volume of alcohol contained in the person’s body, but instead gives a percentage of how much alcohol is present as a ratio compared to the volume of blood measured.
An average 140lb (pound) woman will typically land just under the legal limit of .08 BAC with 2 drinks, bringing her to .07 BAC. A 180lb man will generally hit .07 BAC with 3.5 drinks. That being said, there are certainly variances from person to person and drinking the same amount can cause anywhere from a .06 to a .09 BAC in some people.
Knowing the mathematics of blood alcohol content can help a person avoid drinking over the legal driving limit of .08 BAC. Usually, a woman can consume one drink, and a man two drinks, and safely remain under the legal limit.