Free tool

ABV to Proof Converter

In the US, proof is exactly twice the alcohol by volume (ABV). Enter an ABV to convert to proof, read the reverse to go from proof to percent alcohol, and see an approximate alcohol-by-weight figure. This liquor proof calculator uses the same audited math as Spirit Sight.

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The formula

proof = ABV x 2 | ABV = proof / 2 | ABW ~= ABV / 1.267

A worked example

A 47% ABV gin is 94 proof (47 x 2). A 110 proof barrel sample is 55% ABV (110 / 2). By weight, a 40% ABV spirit is approximately 40 / 1.267 = 31.6% ABW.

Doing this math barrel by barrel? The platform runs the same calculation on every record automatically, reconciled against the books. See it live.

US proof definition (27 CFR 30.11 measures spirits in degrees of proof). This tool uses the same calculation as the Spirit Sight platform. It is general information, not tax or legal advice.

How do you convert ABV to proof?
In the US, multiply ABV by 2. 40% ABV is 80 proof; 45% ABV is 90 proof.
How do you convert proof to ABV?
Divide the proof by 2 to get percent alcohol. 100 proof is 50% ABV; 80 proof is 40% ABV.
What is alcohol by weight (ABW)?
A weight-based measure, roughly ABV divided by 1.267. It is lower than ABV because alcohol is less dense than water, so the same volume percentage is a smaller weight percentage.
Alcohol by weight (ABW) calculatorProof gallon calculatorSpirit dilution calculatorDistillery production softwareEntry proof (glossary)

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