In the US, proof is double the ABV. So a whisky at 40% ABV = 80 proof. A cask strength at 60% ABV = 120 proof.

From the legal minimums that define the spirit to the intense "cask strength" expressions favored by connoisseurs, the alcohol content of whisky is a carefully controlled and fascinating aspect of its production. The Standard Range: 40% to 46% ABV

The most common number you will see on a bottle of whisky is (80 Proof). This is the minimum legal requirement for a spirit to be labeled and sold as "whisky" (or whiskey) in the United States, the European Union, and many other jurisdictions.

So, how much alcohol is in whisky? The short answer is that most standard whiskies sit around . However, the long answer involves legal minimums, "cask strength" beasts, and a bit of math involving "proof."

A standard drink in the US (14g pure alcohol) is found in:

Here’s a concise, informative write-up on the alcohol content in whisky: