You know what ingredients go into your cocktail. You know how much alcohol is in each spirit you mix into your drink. But have you ever wondered what your cocktail’s percentage of alcohol by volume is after adding mixers and shaking with ice?

Yeah, I know. It’s a little nerdy, but interesting all the same.

What you need to know to figure cocktail proof:

1. Exact measurements of each ingredient in your drink. This includes alcohol, mixers, and the amount of ice that melts while shaking the drink.
2. The alcohol content by volume of each ingredient in your drink. This can usually be found somewhere on the front or back label of the alcohol bottle. Alcohol proof is double the alcohol content percentage. If the bottle says 80 proof it contains 40% alcohol by volume.
3. The total liquid volume of your cocktail. One person may shake a cocktail longer than another or use smaller ice than another, so ice melt while shaking a cocktail is a huge variable. There is an easy way to know for sure how much ice has melted while you shake your drink. Strain your shaken drink into a measuring cup that measures ounces before dressing your drink in a proper cocktail glass. Let’s say the liquors and mixer measurements in your drink equal 4.25 ounces. When measuring the drink after shaking it the total volume equals 5 ounces. This means the melted ice measurement equals .75 ounces.

The Formula:

(liquor volume x alcohol volume / total drink volume) x 100 = percentage of alcohol by volume or drink proof.

We’ll use the Raspberry Lemon Drop as an example:

2 ounces 80 proof Vodka (40% alcohol)

1/4 ounce 33 proof Raspberry Liqueur (16.5 % alcohol)

1-1/2 ounce Lemon Juice (0 alcohol)

1/2 ounce Simple Syrup (0 alcohol)

3/4 ounce Shaken Melted Ice (0 alcohol)

Total: 5 ounce drink

[(2 ounces multiplied by 40%) plus (.25 ounce multiplied by 33%)] divided by 5 ounce drink volume multiplied by 100 equal percentage of alcohol by volume or drink proof.

[(2 x .4) + (.25 x .165)] / 5 x 100

[.8 + .04125] / 5 x 100

.84125 / 5 x 100

.16825 x 100

16.825% alcohol by volume

33.65 proof

Now wasn’t that fun and easy! Now it’s your turn. Go make a drink and figure its total percentage of alcohol by volume.

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All content ©2015 Cheri Loughlin, The Intoxicologist. All Rights Reserved. Chat with Cheri @Intoxicologist on Twitter and facebook.com/Intoxicologist