Question: What does proof mean when referring to alcoholic beverages?
Answer: Proof is defined as twice the alcohol (ethanol) content by volume. For example, a whisky with 50% alcohol is 100-proof whiskey. Anything 120-proof would contain 60% alcohol, and 80-proof means 40% of the liquid is alcohol.
What’s the History of Proof in Alcohol?
The word proof came about in the 18th century when sailors, unloading their ships of cargo and whiskey, had only one way to tell the strength of the liquor they were carrying: they would mix a little bit of whiskey with a pinch of gunpowder and drop a lighted match into the mixture. If it ignited with an audible “proof!”, the sailors knew at least half the content was alcohol.
How Do We Measure Alcoholic Content Today?
Today, we measure alcohol content as alcohol by volume (ABV), or the percentage of the liquid in the bottle that is alcohol, even though proofs can be found on the labels of distilled spirits.