<P> In the United States, alcohol content is measured in terms of the percentage of alcohol by volume . The Code of Federal Regulations (27 CFR (4 - 1 - 03 Edition) § 5.37 Alcohol content) requires that liquor labels must state the percentage of ABV . The regulation permits, but does not require, a statement of the proof provided that it is printed close to the ABV number . For bottled spirits over 100 mL containing no solids, actual alcohol content is allowed to vary within 0.15% of ABV stated on the label . Alcohol proof in the United States is defined as twice the percentage of alcohol by volume . Consequently, 100 - proof whiskey contains 50% alcohol by volume; 86 - proof whiskey contains 43% alcohol . In the United States the term "degrees proof" is normally not used . For example, 50% ABV would be described as "100 proof" rather than "100 degrees proof". </P> <P> Canada labels by percentage of alcohol by volume . The old UK proof standard was still in use as late as 1972 . </P>

An alcoholic beverage which is 80 proof is