Walk down the whisky aisle of any liquor store, and you’ll be confronted by a sea of numbers on bottle labels: 40%, 43%, 46%, 57.8%, and even cask strength offerings nearing 70%. To the uninitiated, these figures can seem like arbitrary marketing. But for the distiller and connoisseur, the alcohol by volume (ABV) is the DNA of the spirit—dictating flavor, mouthfeel, value, and legality.
When distilling, the "heart" of the run comes off the still at a very high proof (often 70-80% for column stills, lower for pot stills). The distiller decides where to cut it.
Here is everything you need to know about the alcohol percentage of whisky. In most major whisky-producing nations—including Scotland, the US, Canada, and Ireland—the legal minimum ABV for whisky is 40% . You will very rarely find a bottle below this threshold labeled as "whisky."
As whisky ages in a barrel, alcohol evaporates faster than water. In a hot, dry climate (like Kentucky or Texas), a 10-year-old bourbon might drop from 62.5% to 55% ABV. In a cool, humid climate (like Scotland), the ABV tends to drop slower, but the total volume decreases.
