Alcohol proof

Alcohol proof (usually termed simply "proof" in relation to a beverage) is a measure of the content of ethanol (alcohol) in an alcoholic beverage. The term was originally used in England, and from 1816 was equal to about 1.75 times the percentage of alcohol by volume (ABV). The United Kingdom changed to use ABV instead of proof. The definition of proof in terms of ABV varies from country to country; for example, in the United States, alcohol proof is defined as twice the percentage of ABV. The measurement of alcohol content and the statement of content on bottles of alcoholic beverages is regulated by law in many countries. In 1972, Canada phased out the use of "proof"; in 1973, the European Union followed suit; and the United Kingdom, where the concept originated, started using ABV instead in 1980. The United States Code mandates the use of ABV, but permits proof to be used also. The degree symbol (°) is sometimes used to indicate alcohol proof, either alone (e.g. 10°) or after a space and joined to the letter P as a unit name (e.g. 13 °P).