Refers to the alcohol content of a beverage. In the United States, proof represents twice the alcohol content as a percentage of volume. Thus, a 100 proof beverage is 50% alcohol by volume and a 150 proof beverage is 75% alcohol. In the Imperial system, proof, (or 100% proof), equals 57.06% ethanol by volume, or 48.24% by weight. Absolute or pure ethanol is 75.25 over proof or 175.25 pro