What does proof measure in relation to distilled spirits?

Proof is a standardized measure of the strength, or alcohol content, of distilled spirits. Specifically, it quantifies the amount of alcohol (ethanol) contained in the beverage, which is expressed as a percentage of the total volume. In the United States, proof is calculated as twice the percentage of alcohol by volume (ABV). For example, a spirit that has 50% ABV is considered to be 100 proof.

Understanding proof is critical for both consumers and bartenders, as it influences factors such as the effect of the drink on the consumer, the mixing of cocktails, and the legal regulations surrounding alcohol sales. While flavor profiles, quality classifications, and pricing are important aspects of distilled spirits, they do not relate directly to the proof measurement. Only the strength of an alcoholic beverage, reflected through proof, provides a direct insight into the alcoholic potency of the product.