Free tool

Proof Gallon Calculator

A proof gallon is one US liquid gallon of spirits at 100 proof (50% ABV), and it is the unit the TTB uses for excise tax and operational reports. Enter your wine gallons and proof below to convert to proof gallons instantly. This tool uses the same audited proof-gallon math as Spirit Sight, so it never disagrees with the product.

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The formula

proof gallons = wine gallons x (proof / 100)

A worked example

A full 53-gallon barrel entered at 125 proof holds 53 x 125 / 100 = 66.25 proof gallons. The same barrel filled at 110 proof would hold 58.3 proof gallons, which is why entry proof changes your tax and yield math from day one.

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

27 CFR 30.36 (definition of proof gallon). This tool uses the same calculation as the Spirit Sight platform. It is general information, not tax or legal advice.

What is a proof gallon?
One US liquid gallon of spirits at 100 proof (50% alcohol by volume). It is the TTB unit for excise tax and operational reporting.
What is the proof gallon formula?
Proof gallons = wine gallons x proof / 100. Multiply your wine gallons by the proof, then divide by 100. A 53-gallon barrel at 125 proof is 53 x 125 / 100 = 66.25 proof gallons.
How do you convert wine gallons to proof gallons?
Multiply the wine gallons (the actual liquid volume) by proof / 100. To go the other way, from proof gallons to wine gallons, divide proof gallons by proof / 100.
Is a proof gallon the same as a wine gallon?
No. A wine gallon is a liquid gallon regardless of strength; a proof gallon adjusts for alcohol content by the factor proof / 100. They are only equal at exactly 100 proof.
ABV to proof converterFederal excise tax calculatorTTB gauging calculatorTTB reporting softwareProof gallon (glossary)

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