A few weeks ago I ended up in what turned into a heated debate about alcohol proof and ABV. While out drinking, a friend of a friend remarked that he had a bottle of 100-proof liquor at his house, ...
Proof is a measure of the alcohol content of a beverage. In the U.S., policymakers define proof as twice the percentage of alcohol by volume (ABV). For example, a drink with 40% ABV is 80 proof.