Walk into any whiskey bar or browse a liquor store shelf, and you’ll see it prominently displayed: a number followed by “% ABV” or the synonymous “Proof.” For American whiskeys, you might even see both (e.g., “45% ABV / 90 Proof”). But this number is far more than a legal requirement or a warning label. It is a fundamental key to a whiskey’s character, influencing everything from its aroma and flavor to its mouthfeel, price, and even its history.
Distilleries use two main systems to label the alcohol concentration of a spirit bottle:
The raw, unadulterated spirit as it comes from the barrel (e.g., George T. Stagg, Booker’s, many single cask releases).