What Does An Alcohol's 'Proof' Actually Mean?

By Lynne Rossetto Kasper

Dear Lynne,

Liquor labels always say, "proof," like, "80 proof." What does "proof" actually mean?

Douglas from Minneapolis

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Dear Douglas,

At first glance proof's definition makes no sense. It seems needlessly complicated.
Proof is the government documentation of a distilled beverage's alcohol content. In the United States if you cut the number in half and you get you get the actual amount of alcohol in the bottle. Eighty proof means 40 percent of the liquid in the bottle is alcohol. Why use proof when you could simply state 40 percent on the bottle?

Proof started because of buyer beware. It began here during our 18th century whiskey trade. Whiskey took off when farmers realized they could make ten times the money on their corn if they distilled it. As the market soared so did watering down the booze for even more money.

Suspicious buyers came up with a "gunpowder proofing," testing method. They mixed the whiskey with gunpowder and lit it. If the gunpowder exploded, the liquor had no water in it and it was "proofed." And so was anyone standing nearby. This became the official term for pure whiskey. Please do not try this at home.

Lynne Rossetto Kasper is the host of The Splendid Table®, American Public Media's national food show and co-author of The Splendid Table's How to Eat Supper: Recipes, Stories and Opinions. Ask questions and find Lynne, recipes, and station listings at, or 800-537-5252.

Copyright 2011 Lynne Rossetto Kasper