How much does whiskey proof rise during aging?

Here's why:

* Proof is a measure of alcohol content: Proof is simply a way of expressing the percentage of alcohol by volume (ABV) in a spirit.

* Aging doesn't change alcohol content: The aging process in whiskey barrels involves evaporation of water, not alcohol. This process is called the "angel's share."

* Proof can *decrease* during aging: Because water evaporates faster than alcohol, the ABV actually *slightly decreases* during aging. This means the proof will also go down, not up.

In conclusion: Whiskey proof is not affected by the aging process in a positive way. The proof usually stays the same or decreases.