Proof

Definition and meaning

Proof is a unit of alcohol strength, especially in the USA. American proof is defined as twice the alcohol percentage ABV: Proof = ABV × 2. A spirit with 40% ABV is therefore called 80 proof.

Formula

Proof = ABV × 2.

Applications and examples

• 50% ABV → 100 proof.
• 40% ABV → 80 proof.
• 75.5% ABV → 151 proof.

Historical context and notes

In other countries, different scales are often used to indicate alcohol strength. In Britain, proof was historically defined differently and not as the American double-ABV system; in modern practice, ABV is normally the dominant unit of measurement. In the USA and in modern marketing, proof is therefore a convention that provides a quick impression of the strength without having to calculate in ABV.

Related concepts

• ABV (Alcohol By Volume)
• Spirit strength
• TTB (Alcohol and Tobacco Tax and Trade Bureau)