Bourbon pouring into glass from bottle
Food - Drink
How To Understand The Strength Of Bourbon When It's Bottled
The Pure Food and Drug Act of 1906 outlined that the ingredients and proof of bourbon must be put on its label. It helped define how strong a bourbon is once it hits the shelves.
The proof of an alcoholic liquid is usually double its ABV (alcohol by volume) measurement. For example, a bottle of bourbon labeled 45% ABV will be measured at 90-proof.
The higher the proof of bourbon, the stronger it is. Bourbon can't be distilled at higher than 160-proof, barrelled higher than 125-proof, and has to be at least 80-proof.
There are no caps on how high the bottled bourbon's proof lists, but at 100-proof, the bourbon can be listed as "bottled in bond," which is a whole other distinctive designation.