Alcohol Proof, Proof Gallons and Dilution
Alcohol proof, proof gallons, the federal excise tax, and the water to add to reduce proof (federal gauging rule).
Open the tool → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- What to work out
- Percent by volume and proof
- Convert: percent ethanol by volume
- 95
Result: 95% by volume is 190 proof.
The tool opens with these values already filled in. Replace them with your own.
What you enter
- What to work out: percent and proof (convert), proof gallons (gallons), tax, or water to add to reduce proof (reduce)
- Convert: percent ethanol by volume (give this or the proof)
- Convert or gallons: proof
- Gallons: volume of spirits
- Gallons: unit of the volume (wine gallons or liters)
- Tax: proof gallons
- Tax: rate in dollars per proof gallon (26 U.S.C. 5001; which rate applies is the reader's to say)
- Reduce: starting proof
The other 4 fields
- Reduce: wanted proof
- Reduce: wine gallons on hand
- Reduce: parts water at the starting proof, from Table 6 of 27 CFR 30.66
- Reduce: parts water at the wanted proof, from Table 6
How this is calculated
Citation
27 CFR 30.11 (proof is twice the percent of ethyl alcohol by volume at 60 °F; a wine gallon is 231 cubic inches), 30.31(a) and 30.66 (Table 6 reduction); 26 U.S.C. 5001(a)(1) and (c)(1), 2024 edition, for the tax rates. Read the sources: 27 CFR 30.66 ↗, 26 U.S.C. 5001 ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.