Blood Alcohol Concentration (BAC) Practice Exam

A standard drink is defined by a fixed amount of ethanol, not by the beverage’s size. In the United States, one standard drink contains about 14 grams of pure alcohol, which is roughly 0.6 fluid ounces. That amount translates to common beverages delivering similar ethanol: about 12 ounces of beer at around 5% ABV, about 5 ounces of wine at around 12% ABV, or about 1.5 ounces of 80-proof distilled spirits (40% ABV). The point of this definition is to make it easy to compare how much alcohol you’re consuming across different drinks, since the actual liquid volume varies with the beverage type and its strength. So, regardless of whether you’re drinking beer, wine, or liquor, a standard drink aims to deliver roughly the same amount of ethanol, which is what influences BAC.