Updated March 2026.
In the United States, whiskey proof is twice the alcohol by volume. 80 proof is 40% ABV. 100 proof is 50% ABV. TTB defines proof as the ethyl alcohol content at 60°F, stated as twice the percent alcohol by volume. The required label statement is still percent alcohol by volume; proof is optional and must sit in the same field of vision if used.
Whiskey bottled for the US must be at least 40% ABV / 80 proof (27 CFR 5.143). Below that, it is not whiskey. Most supermarket bourbon is 80–90 proof. Barrel-proof is whatever came out of that barrel after water — read the batch.
Proof vs a 1.5 oz pour
| Label | ABV | Std drinks in 1.5 oz | Notes |
|---|---|---|---|
| US whiskey minimum | 40% | 1.00 | 80 proof |
| Common 86–90 proof | 43–45% | ~1.08–1.13 | Many “extra aged” SKUs |
| 100 proof / bottled-in-bond | 50% | 1.25 | See 100-proof meaning |
| Barrel-proof example 120 | 60% | 1.50 | Batch-specific |
US proof is not the old British gunpowder test and not the obsolete UK Sikes scale (where 100° proof was about 57% ABV). If a bottle says 40% alc/vol and 80 proof, those agree. See vodka proof for the same US math on a different class.
A 1.5-ounce 80-proof pour is one NIAAA standard drink (14 g alcohol, updated December 2025) and about 97 calories (USDA). 100 proof in the same jigger is 1.25 drinks. Proof is not a flavor grade. For drink count see how much whiskey to get drunk.
Sources
- TTB distilled-spirits FAQs: proof = 2 × % ABV.
- TTB labeling: % ABV required; proof optional in the same field of vision; ±0.3 percentage-point tolerance.
- 27 CFR 5.143: whiskey bottled at not less than 40% ABV.
- NIAAA standard drink (December 2025).