When shopping for spirits, you might see two different values on labels: "ABV," or alcohol by volume, and "proof." That second one isn't always there, as distilleries in the United States aren't ...
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.