What Is the Proof of My Cocktail?

Calculating the Alcohol Content of Mixed Drinks

Scientist tasting whiskey in plant

 Monty Rakusen/Getty Images

It is easy to tell how strong liquor is because you simply need to read the bottle's label and look for its proof or alcohol by volume (ABV). This will tell you whether the whiskey or vodka you're pouring is the standard 80 proof, or a little higher or lower. Yet, have you ever wondered about the proof of your cocktail?

Things can get complicated when you start combining different liquors with nonalcoholic mixers, shaking it with ice and adding water, and everything else that is required to create great drinks. Unless you are willing to carry a test kit filled with scientific gadgets to the bar, there is no straight answer as to how strong the drink in front of you is in reality.

There is, however, a simple formula that can help you estimate the alcohol content of your mixed drinks. It can also help you decrease or increase a drink's potency if you know a few basic facts.

Measuring the ABV of Liquor

There are two numbers on every liquor bottle that indicate exactly how strong the distilled spirit is: alcohol by volume (ABV) and proof. The two can easily be converted back and forth, though they have different purposes.

What Is ABV?

Alcohol by volume often reads as alc/vol or ABV on the label. It is given as a percentage and measures the amount of alcohol that is in a bottle compared to the total volume of liquid.

During the distillation process, the distiller will produce a very strong distillate that comes directly out of the still. This is then watered down to the bottling strength, or the alcohol by volume indicated on the label.

ABV is required on every alcoholic beverage sold on the legal market worldwide, including all liquor, wine, and beer.

What Is Proof?

The proof is a number that is primarily used in the United States to denote the taxes a distiller needs to pay on a certain amount of liquor. American drinkers tend to use proof to describe the potency of liquor as well. It is easier than saying alcohol by volume or alcohol content (neither sounds as cool as proof)

Proof is only used on distilled spirits; you will not find the word on beer and wine labels.

The Average ABV

The alcohol content for most alcoholic beverages falls into a certain range:

  • Brandy, gin, rum, tequila, vodka, and whiskey are typically 40 percent ABV or 80 proof. Some high-proof liquors—primarily whiskeys and rums—reach over 50 percent ABV (100 proof). You will also notice that many flavored vodkas and similar liquors are bottled at 35 percent ABV (75 proof).
  • Liqueurs tend to range from 15 to 30 percent ABV or 30 to 60 proof. Some, such as Cointreau and Bénédictine, are 40 percent ABV (80 proof).
  • Beer can range from 3.0 percent to 13.0 percent ABV, though most fall somewhere between 4.0 percent and 7.0 percent. The decimal point is almost always included (e.g., 4.2 percent) because brewers indicate the exact percentage of each brew.
  • Wines tend to range from 8 to 14 percent ABV.

Tip

If you do some quick math, you'll notice the easy formula used to switch between ABV and proof:

ABV x 2 = Proof

For example:

  • 40 percent ABV is 80 proof
  • 15 percent ABV is 30 proof

Estimating the Alcohol Content of Mixed Drinks

Why did you get drunk off just two vodka martinis last night when the other day you felt fine after three whiskey highballs? The more you look at the alcohol content of cocktails, the more you realize that some may be all short and fancy, but they're surprisingly potent!

More drinkers are becoming concerned about how strong their mixed drinks and some bars are even adding ABV to their cocktail menus. The reputation of certain styles of drinks or the liquor that goes into them can also cause you to perceive that a cocktail is stronger or lighter. When you learn how to estimate a drink's true alcohol content, you can have greater control when making decisions about what to drink when.

These calculations can only be an estimate of a drink's strength because of a few factors. One of the biggest unknowns in the formula is how the drink is mixed. Every professional and home bartender mixes drinks a little differently:

  • Some shake harder, causing more ice to dilute the drink.
  • Some will pour a 2-ounce shot of liquor while others prefer 1 1/2 ounces.
  • Some fill a highball drink with 6 ounces of ginger ale while others only use 4 ounces.

The size of the glass, particularly when building drinks, is also going to play a role in the drink's strength. If you are using a 7-ounce collins glass, for instance, you will have a stronger drink than if you make the same drink in a 10-ounce highball glass and fill it with soda. It's a simple matter of diluting down the alcohol with a nonalcoholic ingredient.

The Cocktail Proof Formula

While you cannot know the exact alcohol content of any particular mixed drink, there is a basic formula that's used to estimate a drink's strength:

(Alcohol Content x Liquor Volume / Total Drink Volume) x 100 = % Alcohol by Volume

It's a bit confusing at first, but once you get the hang of it, it's relatively simple.

A Martini Is Stronger Than You Think

The classic gin martini recipe is a perfect example. To estimate its strength, begin by breaking down each of the alcoholic ingredients; multiply the volume of each by their individual strength. You must also factor in dilution because this adds to the drink's total volume. To keep things simple, 1/2 ounce allowance is used for dilution for all cold mixed drinks.

Ingredient Volume Standard ABV
2.5 oz gin - 40% (.40) ABV or 80 proof
.5 oz dry vermouth - 15% (.15) ABV or 30 proof
.5 oz melted ice - standard dilution allowance

With that information, you will add up the total alcohol content per liquor volume. You will also need to add up the drink's total volume. 

( .40 x 2.5 ) + ( .15 x .5 ) = 1.075 2.5 + .5 + .5 = 3.5 oz
(alcohol content x liquor volume) (total drink volume)

These two numbers are then plugged into the cocktail proof formula:

  • 1.075 / 3.5 = .30 x 100 = 30% ABV or 60 proof

The result is that the average gin martini is 30 percent ABV or 60 proof. That is a very strong drink, which is understandable because it is made of only gin and vermouth. The ice brings it down just slightly below the gin's bottling proof. Of course, this will vary if you prefer less gin and more vermouth in your martini.

And yet, this is a good reminder that the average martini is almost as strong as a shot of tequila. You will find that similar all-alcohol "up" drinks (e.g., Manhattan and rusty nail) are just as strong.

Tall Drinks Are Lighter

Not all mixed drinks are that strong, though. Many favorite casual-sipping drinks include juices, sodas, and other nonalcoholic mixers at high volumes (2 ounces to 6 ounces) that significantly reduce the impact of the alcohol.

For a simple highball drink, the Tom Collins is a good example. Since gin is the only liquor, it is the only ingredient that requires the initial alcohol content calculation. The other ingredients are simply factored into the drink's total volume.

1.5 oz gin - 40% (.40) ABV or 80 proof
1 oz lemon juice  
.5 oz simple syrup  
3 oz club soda  
.5 oz melted ice  
   
( .40 x 1.5 ) = .60 1.5 + 1 + .5 + 3 + .5 = 6.5 oz
(alcohol content x liquor volume) (total drink volume)

Just like the martini, simply plug these two numbers into the cocktail proof formula:

  • .60 / 6.5 = .09 x 100 = 9% ABV or 18 proof

The strength is about one-third of the martini and more in-line with drinking a glass of wine.

Frozen Cocktails Are Tricky

Whenever you mix a drink in the blender, ice plays a more significant role because it becomes part of the drink, not simply a means to cool or dilute. That means estimating the strength of frozen cocktails is even less exact. Yet, there is a guideline that can help out.

Most frozen drink recipes suggest adding 1 cup of ice to the blender; about 5 or 6 average-sized ice cubes makes 1 heaping cup. When those are blended on their own, the result is about 4 ounces (or 1/2 cup) of shaved ice. That number can then be inserted into the cocktail proof formula.

The basic frozen lime margarita is a good example for this category because there's no whole fruit to factor in.

1 cup ice 4 oz blended
1.5 oz tequila 40% (.40) ABV or 80 proof
.5 oz triple sec 30% (.30) ABV or 60 proof
1 oz lime juice  
2 oz sour mix  
   
(.40 x 1.5) + (.30 x .5) = .75 4 + 1.5 + .5 + 1 + 2 = 9 oz
(alcohol content x liquor volume) (total drink volume)

Once again, plug those two numbers into the cocktail proof formula:

  • .75 / 9 = .08 x 100 = 8% ABV or 16 proof

That frozen margarita is the same strength as the average tall mixed drink. This type of cocktail will only get lighter as you add fruits or ingredients like milk or ice cream, too.

Alcohol Content and Liqueurs

Liqueurs are a great variable in this equation. While you can generally assume that gin, vodka, whiskey, and other base spirits are 80 proof (and the bottle will clearly state otherwise), liqueurs are not so easy. Different liqueurs will have different alcohol content. They will vary from one brand to another, even between liqueurs of the same style or flavor.

The vast range of orange liqueurs is a perfect example:

  • Triple sec tends to be 30 percent ABV (60 proof) or less.
  • Grand Marnier and Cointreau are both bottled at 40 percent ABV (80 proof).

Both of these top-shelf liqueurs have the same alcohol content as most of the rums and tequilas that they are often mixed with. Therefore, a margarita made with Cointreau will naturally be stronger than one made with the average triple sec.

Even two different brands of the same liqueur may have different alcohol contents. Let's break triple sec down even further:

  • Arrow triple sec is 17 percent ABV (34 proof).
  • Bols triple sec is 21 percent ABV (42 proof).

If alcohol content is a concern for you, then you will want to pay attention to the bottle's label. Though, at times (such as in this particular brand comparison), you may also be sacrificing quality by going with the lower-proof option.

Online Calculator

If you would like to know the proof of a particular cocktail without doing the math yourself, you can use an online tool. The Cocktail Content Calculator on the National Institutes of Health's Rethinking Drinking website is a good one.

This is a very handy tool that will estimate the alcohol content of a certain recipe. It is only a generalized tool and should not be used to test the true proof of any drink because it does not take all of the factors involved into account.

The Take-Away

Are you going to add up the alcohol content of every drink you make? Probably not! After all, there's a cocktail to drink, right? However, you can use these estimates to get a sense of how strong a particular style of drink is going to be so you can make an informed decision. There are a few generalizations you can apply with every drink:

  • Martinis and similar "up" drinks can be almost as strong as shooters.
  • Fruity martinis like the cosmopolitan will be a little lighter, though still around 20 percent ABV (40 proof)
  • Drinks served on the rocks with no or few mixers, such as the old-fashioned, will be very potent as well.
  • The taller the glass and the higher volume of nonalcoholic mixers, the lighter the drink.
  • Blended cocktails are among the lightest you can mix up (unless you overpour, which many people do).