Proof vs ABV: How to Read the Strength on a Spirits Label
Pick up a bottle of American whiskey and you'll often see two numbers: something like "45% alc./vol. (90 proof)." One is required. The other is optional, and it means something different depending on which country's history you ask. Here's what each number means, what the label rules say, and the conversions worth knowing. The short answer: in the US, proof is twice the ABV US law defines proof as the alcohol content at 60°F, "stated as twice the percent of ethyl alcohol by volume". So: % alcohol by volume US proof 40% 80 45% 90 50% 100 75.5% 151 95% 190 For US proof, that's the whole conversion: multiply ABV by two to get proof, or halve the proof to get ABV. What a US label has to say Alcohol by volume is mandatory. Federal rules require the alcohol content of distilled spirits to be stated as a percentage by volume. Proof is optional. A label can show it, as long as it's in the same field of vision as the ABV statement. TTB...