is a bit different. In the United States, proof is exactly double the ABV. So, an 80-proof whiskey is 40% ABV. (Fun fact: The UK and US define proof differently historically, but the double rule is standard in the US today.)
If you’ve ever flipped a bottle of whiskey to read the fine print, you’ve seen it: a number followed by the letters ABV (Alcohol by Volume), and often another number followed by the word Proof . whiskey alcohol content percentage
Drink responsibly. Know your limits.