Determining the alcohol content of your liqueur

As you begin experimenting with making your own liqueurs, you’ll invariably run up against the “what percentage of alcohol is this?” question. It can be tricky. You can measure the amount of alcohol in a pure base spirit by measuring its specific gravity. This is done with a hydrometer (found in all home brewing supply shops). Once a spirit is diluted with anything besides distilled water, the reading will lose accuracy – all bets are off. You can no longer use a hydrometer to measure the concentration if you’ve added any sugar, or any other soluble substance to your base spirit. It won’t be anywhere close to accurate.

In calculating the alcohol content of your creation, you must always begin with the alcohol content (by volume) of the base ingredients. If you don’t have that, you will not be able to compute your alcohol content. Sure, you could take a stab in the dark by liqhting your creation (a concentration will sustain a flame right around 40% ABV) but why resort to something of questionable safety (or worse, consume some of the alcohol of your precious hard work)?

Proof versus Alcohol By VolumeFirst, let’s get some definitions here. “Proof” is the concentration of alcohol in an alcoholic beverage. This traditional term reportedly arose from “proving” the alcohol concentration of rum rations in the British Navy. It has a mathematically direct relationship with alcohol percentage by volume. Proof is twice the percentage of alcohol (by volume). Thus, 80 proof vodka contains 40% alcohol by volume. The maximum possible proof of beverage grade ethanol is right around 196. Any higher concentrations aren’t considered beverage grade, and usually absorb moisture from the air, bringing their concentration back down.

Typical alcohol concentrations

In calculating our alcohol content, we always begin with our base ingredients. I often start with a neutral grain spirit at 190 proof (95% alcohol by volume). Here are some typical concentrations:

Vodka, Gin, Whiskeys: 38% – 45% ABV (76 – 90 proof)

Brandy: 40% ABV (80 proof)

Vermouth (fortified wines): 17-23% ABV (35 – 46 proof)

151 Rum: 75% ABV (151 proof)

Grain alcohol: 75% – 96% ABV (151 – 192 proof)

When creating your liqueur, the first thing to do is to determine the actual amount of ethanol in your base spirits. Take the volume of the spirit in liquid measure (fluid oz, cups, ml) and multiply it by the percentage of alcohol by volume. Divide that amount by 100. That will be the liquid measure of ethanol in your base.

(Total Volume X Percentage of Alcohol) divided by 100

For example: Let’s say we’re creating an amaro that begins with 2 cups (16 oz) of grain alcohol at 75% ABV

1) Multiply alcohol volume by its ABV concentration:
16 X 75 = 1200

2) Divide the product by 100:
1200 ÷ 100 = 12

There are 12 oz. of ethanol in our 2 cups of grain alcohol at 75% ABV.

This is the alcohol liquid measure that will (more or less) remain constant for all of your concentration calcuations of this particular batch (assuming little evaporation).

Now, the alcohol percentage of your finished amaro, liqueur or spirit can be calculated by dividing the original alcohol liquid measure by the total volume of your finished spirit. If two cups of liquid (water, infusions, syrup) are added to the 2 cups of grain alcohol, the total spirit volume is, of course, 4 cups. The resulting spirit is now:

12 oz ethanol ÷ 32 oz (4 cups) = 37.5% ABV or 75 Proof

Note that this is completely different than comparing the specific gravity of wort and the finished beer to determine ABV. In that case, no additional liquid is added so the process is more or less isochoric (constant-volume).

How about adding different spirit components?

Determining alcohol content when adding different components isn’t much more difficult either. Let’s say you’re creating a liqueur by adding a cup of brandy at 80 proof, a cup of sweet vermouth at 34 proof, and a cup of grain alcohol at 151 proof. How do we calculate the combined concentration?

We begin by calculating the liquid measure of alcohol of each component separately:

1 cup (8 oz) of brandy at 80 proof

8 oz X 40% ABV = 320
320 ÷ 100 = 3.2
3.2 oz of alcohol in 1 cup of brandy

1 cup (8 oz) of sweet vermouth at 34 proof

8 oz X 17% ABV = 136
136 ÷ 100 = 1.36 or 1.4
1.4 oz of alcohol in 1 cup of vermouth

1 cup (8 oz) of grain alcohol at 151 proof

8 oz X 75% ABV = 600
600 ÷ 100 = 6
6 oz of alcohol in 1 cup of grain alcohol

Add the alcohol liquid measures together: 3.2 + 1.4 + 6 = 10.6 oz of alcohol

Add the total spirit volume: 3 X 8 oz = 24 oz.

Thus, the alcohol content of combining all three ingredients together: 10.6 oz alcohol ÷ 24 oz total volume = .441 or 3 cups at 44% ABV (88 proof).

Simple, isn’t it?

How to determine the amount of liquid to dilute a spirit to a desired concentration

This seems tricky at first, but it really isn’t. To find out how much liquid to add, begin by getting the alcohol content of the existing concentration. Using the example above, we have 10.6 fluid oz of alcohol in 3 cups. To find the amount to add, divide the alcohol liquid measure by the desired concentration (% ABV in decimal form) to get the new total spirit volume. Subtract the original total spirit volume and you’ll have the amount of liquid to add to bring it to a desired concentration.

In other words:

If we want to dilute the above example so that it’s final concentration is a 30% ABV,

1) Get the alcohol liquid measure of the solution as it is now:
10.6 oz

2) Divide that by the desired concentration percentage:
10.60 ÷ 0.30 = 35.33 oz (total spirit volume)

3) Subtract our original volume:
35.33 – 24 = 11.33 oz.

We would need to add 11.3 oz of a non-alcoholic liquid to drop the concentration down to 30% ABV.

Equally simple, right?

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10 thoughts on “Determining the alcohol content of your liqueur

  1. Hi

    Thanks so much for posting this. It is quite helpful. I just have one question, what about cream liqueur? I am aware that ABV is actually measured by relative density rather than actual volume.

    Thanks.

    • Measuring the content of any single component (solute) in solution becomes quite literally impossible once there is more than one solute dissolved in that solution. Alcohol is no exception. If you have a mixture of alcohol (ethanol) and water, you can determine the proof by its relative density (also known as specific gravity). Once you add anything to that mixture (sugar, flavoring, oak, etc.) the alcohol content cannot be measured (at least not without more complex calculations). It can only be computed from the original content in the neutral spirit.

      For a cream liqueur, the only way to know its alcohol content is to know how much ethanol (fluid measure) was used in the original components of the liqueur. Because the liqueur has a solvent (cream or condensed milk) without a specific gravity of 1.00 (water), a basic hydrometer cannot be used to measure its specific gravity accurately. Using the computations as shown in this post, if you know the alcohol by volume that was added to the ingredients in the cream liqueur, you can determine the ABV.

      The measure of alcohol in fermentation is found a different way – you take a before and after reading (specific gravity) of the wash during fermentation. Through computation, you can determine the alcohol content of the fermented wash.

      I hope that helps.

      K

  2. Is there any way to tell the content of the alcohol after it has been soaking in berry’s or fruits or it has been run through a basket?

    Any suggestions? I ask because it is hard to tell the water content of fruits to judge.

    Thanks

    • Hi Stephen,
      No, there isn’t a way to measure the alcohol content once you’ve added anything other than dried ingredients. The only way to know is to keep track of the volume of alcohol you started with. That should remain constant (minus some evaporation which with care, should be negligible). Divide that amount by your total volume and it should be pretty accurate.

  3. Pingback: Making Homemade Liqueurs and More

  4. I’m making limoncello liqueur using 1L of 95% alcohol. I would like to achieve 27% ABV once limoncello is ready, and using your method above, I would need to add some 2.5L of water to achieve this result. I will also be adding 1.2kg of sugar to the water to make the syrup. My question is will this be reducing the ABV even further? Or as long as I have 2.5L of syrup (water and sugar) I should be fine?

    • Exactly! If you’re diluting your limoncello by 2.5L – that has to include everything – water and sugar. Remember, ABV is based upon volume, so the amount of sugar doesn’t matter – as long as the addition of any non-alcoholic liquid measures 2.5L by your measure.

  5. Hello, I’m wondering if these calculations are accurate enough to meet trading standards? If I wanted to make and sell fruit infused alcohol online as a business, would these calculations be sufficient? Anyone done this?

    • The short answer I’ll give you is “it depends, but probably not.” These calculations are accurate as long as you are able to minimize evaporation, and don’t determine alcoholic content after you’ve added other ingredients that change the density or specific gravity of the solution. In other words, your calculations have to take place before the addition of any other liquids other than water, or any solids such as sugar.

      If you want to sell your liqueur, you would need to get the proper permits and certification from the Bureau of Alcohol, Tobacco and Firearms. I believe they require accuracy to around 2% of the actual alcohol in your beverage. The calculations here are not measurements (they’re calculations from a starting point) so they may not satisfy that degree of accuracy. For that you may need a refractometer, establish before and after hydrometer (specific gravity) readings, or use something more sophisticated as an alcohol density meter. You can probably find some of these solutions online.

      Here’s some additional information about methods to measure ABV:

      https://flaviar.com/blog/measuring-alcohol-content

      I hope this helps answer your question. I would urge you to investigate other methods of measuring alcohol content if you’re serious about producing liqueurs as a business.

  6. Kurt,

    Thanks for the post. I wanted to reply to the comment from squarekatie. The TTB(Alcohol and Tobacco Tax and Trade Bureau) formerly part of the ATF, requires spirits to be within a range of .15 proof BELOW the labeled proof. So, for instance if you have a liqueur that is labeled at 40 proof(20%abv) you would have to be able to prove with lab results(the TTB uses two methods depending on the amount of dissolved solids to determine obscuration) that you are at no lower than 39.85 proof and no more than 40 proof.

    See the following videos:
    [video src="https://www.ttb.gov/media/2014-09-19-proofing-sec3-mds_CCSub.mp4" /]
    [video src="https://www.ttb.gov/media/2014-09-19-proofing-sec4-mds_CCSub.mp4" /]

    So Katie, the short answer is no. Hope that is more helpful than it is confusing.

    Rob

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