Decoding Alcohol Proof

Picture this.

You're standing in a liquor store looking at a bottle of vodka.

The label says forty percent alcohol by volume.

Makes sense.

But right next to it, usually in much bigger lettering, it says eighty proof.

Then you walk over to the whiskey or rum section and see another bottle proudly advertising one hundred proof.

And you have to wonder, why do we need two different numbers to describe basically the same thing? And more importantly, does something being one hundred proof mean you're getting dramatically more alcohol? Today, I want to decode one of the most unnecessarily confusing numbers in the alcohol world, because once you understand proof, you'll realize the number itself is actually incredibly simple.

The history behind it, however, is completely ridiculous.

To understand where proof came from, we have to go back centuries.

And like many strange things in history, this one involves taxes.

Governments needed a way to determine how strong distilled spirits were, because stronger alcohol could be taxed differently.

But hundreds of years ago, they obviously didn't have modern laboratory equipment.

So one of the historical methods involved something much more dramatic, gunpowder.

The traditional story is that British sailors would take some of their rum, soak gunpowder with it, and attempt to ignite it.

If the gunpowder still burned, the rum was considered strong enough.

The spirit had been proved.

If it failed to ignite properly, that suggested the rum had been watered down.

So yes, one of the measurements still printed on modern bottles has roots in people literally setting alcohol-soaked gunpowder on fire.

Thankfully, we eventually came up with better technology, but the word proof survived.

And today in the United States, the math is incredibly easy.

Proof is simply twice the alcohol by volume or ABV.

So forty percent ABV vodka is eighty proof.

Fifty percent ABV whiskey is a hundred proof.

Sixty percent ABV rum is a hundred and twenty proof.

If you see the proof and want the percentage, divide it by two.