How to use this calculator
Enter a strength in % ABV to get US proof, or enter US proof to get % ABV. Decimals are accepted, for example 43.5 % ABV or 114.6 proof.
How proof is defined
In the United States, proof is defined as twice the percentage of alcohol by volume:
US proof = 2 × ABV
ABV = US proof ÷ 2The label always says US proof here because other proof systems exist. British proof, which UK spirits used before the switch to % ABV, puts 100 proof at about 57.1 % ABV, so the same number means a different strength. When in doubt, compare spirits in % ABV.
Examples
| % ABV | US proof | Typical of |
|---|---|---|
| 40 | 80 | Standard vodka, gin, whisky |
| 45 | 90 | Many bourbons and rye whiskeys |
| 50 | 100 | Bottled-in-bond US spirits |
| 57 | 114 | Navy-strength gin |
| 95 | 190 | Rectified spirit |
Limitations
- This is a unit conversion only; it does not measure or correct anything.
- Convert a strength that has already been corrected to the standard temperature.
FAQ
How do I convert ABV to proof?
In the United States, proof is twice the alcohol by volume. 40 % ABV is 80 proof, 50 % ABV is 100 proof and 100 % ABV (pure ethanol) is 200 proof.
Is proof the same in every country?
No. This calculator uses US proof. The historical British (Imperial) proof system uses a different scale, on which 100 proof corresponds to about 57 % ABV. Most countries, including the UK, now label spirits in % ABV (% vol) instead of proof.
What does 'cask strength' or 'barrel proof' mean?
It means the spirit was bottled without being diluted to a standard strength, so its proof varies from batch to batch. Convert the stated proof to ABV here to compare it with other spirits.
Does temperature affect proof?
The definition of proof refers to strength at a standard temperature. If you measured strength with an alcoholmeter at another temperature, correct the reading first with the alcohol temperature correction calculator, then convert it.