How To Determine Your Wine's Alcohol Level

Tipsy ManThis is the question every budding home wine maker wants to know, “How can I tell how much alcohol is in my wine?” The problem is, this question is usually asked about the time they’re ready to bottle their wine.  Unfortunately, for the amateur winemaker, this is far to late in the process to make any accurate determinations.
What Needs To Happen
The easiest way to know how much alcohol is in your wine is to take two readings with what’s known as a wine hydrometer: one reading is taken before the fermentation has started and the other reading is taken after the fermentation has finished. By comparing these two hydrometer readings you can determine – with great accuracy – how much alcohol is in your wine.
Very simply put, a hydrometer is a long, sealed glass tube with a weight on one end. By observing how high or low it floats in a liquid you can determine a reading.
“And what are we reading?” Essentially, we are trying to figure out how much sugar is in the wine or wine must. The higher the wine hydrometer floats, the more sugar there is in the liquid, and the opposite holds true as well.
During a fermentation, sugar is what yeast turns into alcohol. If we know how much sugar there was in the wine must before the fermentation, and we know how much sugar there is in the wine after the fermentation, we then know how much sugar was consumed by the yeast during the fermentation. From this information we can determine how much alcohol was made during the fermentation and is now in the wine.
It all sound complicated when it is all explained in detail this way, but in practice it is very easy to accomplish. All you need to do is:
1. Take a wine hydrometer reading at the same time you add the yeast to your wine must. The hydrometer has a scale along it called “Potential Alcohol”. At this point in the wine making process, you should be getting a reading of around 10% to 13%. The reading is the point where the surface of the liquid crosses the scale. This reading indicates how much alcohol the wine can have if all the sugars are fermented. Write this number from the gravity hydrometer down and save it for later.Shop Hydrometers
2. Take another reading with the hydrometer once the fermentation has completed. This reading should be somewhere around +1 to -1 on the Potential Alcohol scale. By comparing these two gravity hydrometer readings you can determine your wine’s alcohol level. Take the first number you wrote down and from that, subtract the second number.
The Calculations
As an example, if your reading before the fermentation was 12% and the reading after the fermentation was 1%, this means that your wine has 11% alcohol (12 minus 1). If your first reading was 12% and your second reading was -1%, that means your wine has 13% alcohol (12 minus -1).
Another way to think of it is you are monitoring how far along the wine hydrometer’s Potential Alcohol scale the fermentation is traveling. It started at 12 and ended up at -1. That’s’ 13 points along the scale.
Further Information
You can find more information about using a hydrometer to make wine in the book, “First Steps In Winemaking.” Also, the article, “Getting To Know Your Hydrometer” has lots of additional information about using your hydrometer when making wine.
—–
Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.

38 thoughts on “How To Determine Your Wine's Alcohol Level

  1. Dear Mr. Kraus, Thanks for your comments about alcohol testing in wine and beer by using hydrometer before and after fermentation. Probably it may be done during fermentation, too, which allows determining when the fermentation needs to be stopped to get the aimed alcohol content. is it correct? Practically, how many times alcohol content should be tested at winemaking and at brewing?
    Thanks in advanced
    Eugene

  2. Dear E. C. Kraus,

    I always enjoy receiving your winemaking newsletter and read the whole thing. It contains a lot of good advice and winemaking tips, especially for beginners.

    This is why I was surprised to read the article in your September 16, 2017 newsletter, entitled "How to Determine Your Wine’s Alcohol Level". When I was starting out in winemaking, I used the same procedure (subtracting to get the difference between initial and final Potential Alcohol readings) to determine the ABV because it seemed to make sense. With further experience and research I realized that simplistic approach is not accurate.

    The reason for the inaccuracy is that ethanol alcohol has an effect on a hydrometer. Sugar increases buoyancy and increases the hydrometer reading, but alcohol decreases buoyancy and therefore decreases the hydrometer reading. That is why a wine that has fermented to dryness has a negative Potential Alcohol or Brix reading instead of landing at zero (and a Specific Gravity below 1.000 instead of exactly at 1.000).

    Alcohol’s effect on a hydrometer may be much smaller than sugar’s, but it does have enough effect to throw off readings. If there is residual sugar, depending on the amounts the sugar and alcohol may actually cancel each other out, since each has an opposite effect on the reading. In other words, a Brix reading is never accurate once alcohol is present. One should never forget that what a hydrometer really measures is Specific Gravity.

    Fortunately, alcohol’s effect on hydrometer readings is predictable and can be calculated, and a few math-savvy winemaking authors have done so. A quick search of the Internet will give you this equation for a reasonably accurate way to determine the alcohol level of a wine:

    (Initial Specific Gravity – Ending Specific Gravity) x 132 = Percent Alcohol by Volume

    Some versions of the formula use 131 or 133 instead, but that does not impact the answer much. Also, there are formulas that use Brix instead of SG.

    Perhaps you are already aware of all this, but presented an inaccurate method in order to make determining the alcohol level simpler. Personally, I do not think that the above method is that difficult and I am all in favor of accuracy. Also, by having an accurate ABV it is then possible to go on and calculate the residual sugar amount (though that is slightly more complicated and also must take into account the presence of extract).

    If you are interested in more information (including the derivation of the above equation), a friend of mine has done quite a bit of research on the matter and his findings are posted on our winemaking club’s website http://www.rochesterwinemakers.org. Click on Winemaking Info to find articles he has written about potential alcohol, ABV and residual sugar.

    Again, thank you for the newsletter and for being a reliable source for quality winemaking supplies. Sorry that this response is a little late. I’ve been busy making wine!

    Sincerely,
    Jill

    • with greetings
      If you feed the deal during the first fermentation period of each day sugar and nutrients
      Is it enough to read the first and last? Or that each time you feed them you must measure and then compile the readings to get the result?

  3. While not perfect, a good vinometer boasts being accurate to 1/2 percent. So, if you’re not involved in some serious wine competition would this not suffice most amature wine makers. And if for some reason you didn’t get a prefermentation hydrometer reading, wouldn’t "close" be better than nothing? Just wondering!

    Don

  4. Don, thank you for your great comment. The Vinometer is a somewhat accurate way to read alcohol levels in a finished wine. The biggest problem with them, and the reason we prefer the use of a hydrometer, is because they are not accurate at all with wines that have residual sugar left in them. The wine needs to be bone dry for an accurate reading. And for wines that are noticeably sweet, the readings are off the chart.

  5. I have been a scientist since I can remember (which is following the law of diminishing returns) and am puzzeled about people wanting to know accurately a wine’s ETOH. As long as it is clear, takes great and has enough to keep the bugs out, do we really care?? Come on folks, give the poor yeast a break!

    • I think I’ll have to agree with Rick. I make wine because my wife enjoys it. She really doesn’t care if the alcohol content is 10 or 20 percent. If it’s “stronger” she cuts it with soda or something or drinks less, if it’s “weaker” she drinks it straight or drinks a little more. If my friends or family don’t like it they can always drink the “store bought” stuff and my wife won’t mind at all !!

      • I agree Mike; I have been making wine since the early 80’s no one has complaned yet about how my wine tastes; and they are always wanting a few bottles. that tells me it is great. I don’t care about the alcohol content; all I care about is that there is enough to keep the cold off me while I am sleeping. Happy wine making to everyone and better yet Happy drinking

        • Hey, I know I’m jumping in late. I have my first welches grape juice sitting 4 weeks and have done two – 1 ounce tastings. Remember it’s my first so I can only compare to store bought at this point. It was drinkable but sweet and I could tell its immaturity. Don’t worry I followed all the instructions and let it sit in a small (no insect) 70 degree dark closet. It reminds me of a lighter version of Boones Farm sweet wine we drank at 17 yrs old.. So… even though it’s very drinkable at 1 month should I keep it going for a couple more weeks? I’m not looking for that perfect store qlty taste. I just want my first wine asap unless you tell me otherwise. By the way,, I also have a apple cider gallon sitting too made the same time. Can I drink that soon if I want? And…what is your opinion the ABV is on these after just one month? I’ll get a reader after this batch and follow a better operation then. You can look back when you first started and understand. Ha..
          Thanks for reading.

          • After 4 weeks you wine should not be tasting sweet. It should be dry at this point. This is an indication that the fermentation has not completed in a timely matter. I would suggest reading the following to see if any of the follow situations apply to your current batch.
            Top 10 Reasons For Fermentation Failure
            https://eckraus.com/wine-making-failure/

  6. Bob, your observation it correct. You can also think of it as adjusting for the alcohol or sugar left behind during a racking. You are replacing it with a liquid that has now alcohol or sugar… water. While technically sound, most people are not will to go through the math to figure such a minor adjustment. Hopefully, your topping-up volumes are much, much less than a gallon.

  7. Isn’t it true that the readings obtained from the hydrometer must be adjusted depending on how much dilution occurred in the topping-off process? If I added a gallon of water to a 5 gallon carboy during the racking process, then the % alcohol will have to be adjusted, correct?

    • When calculating the ABV of my wine from a kit it had me reading the specific gravity at the beginning, at the start of step two Stabilizing and Clearing which a flavor pack is added and then at the end. My readings are 1.054, 0.995 and 1.020. From what I’ve researched you use the starting SG and then the SG after fermentation which is stopped before step two. So do I use the first two readings or the first and last readings? It’s a big difference in ABV, 8.02% or 4.62%.

  8. hello, any tips on getting the initial hydrometer reading? i have my must in a 5 gallon bucket. no pouches, all the grape chunks are free floating. i attempted using a wine stealer kind of thing but it got clogged from all the chunks floating in the bucket. i just added the yeast tonight. id really like to get a hydrometer reading. is it ok to strain out enough for a clear reading then return the sample to the bucket?

    • M Walker, as long as you sanitize the equipment used for the sample, what you are suggesting is perfectly fine to do.

  9. Hello guys, Im doing a project that involves the use of wine. I want to do the exact estimation of ethanol in my wine samples. So, I have tried 1) Batch distillation 2) Refractive Index analysis method 3) Specific gravity estimation etc. I can even perform Gas Chromatography also,but somewhat confused which method is prefferable..?? I even perform Brix analysis also. Can Someone please give me some suggestions??

    • Amita, actually, the easiest and most accurate method we would recommend is the beginning and ending specific gravity readings. The specific gravity reading can be narrowed down within a ten of a percent and it is also the least expensive way.

  10. I think the original Q was how to determine A WINES alcohol by volume. I think we’re all familiar with the potential alc. in the must using a hydrometer .What is a simple way to determine the alc. without knowing its past history ?

    • Tibor, if you do not record a beginning hydrometer reading, the only practical way for a home winemaker to know the finished alcohol content of the wine is by using a Vinometer. Of all the wine making products that exist, the vinometer is the only one that home winemakers can practically use to test the final alcohol level of a finished wine. It is somewhat accurate when testing a dry wine, but if your wine has any residual sugars, the reading will be thrown way off.
      Testing The Alcohol Of A Finished Wine
      http://www.eckraus.com/blog/testing-the-alcohol-level-of-a-finished-wine

  11. I have a copycat recipe for a mead called Vikings Blod , im a beginner , so i want to know how to get it to 19% alc , is it the amount of honey ? the original is 19%

  12. I think determining the amount of alcohol in a drink is fun, and important. You see, most people drink wine for one of two reasons, or the combination of the two. 1: taste and feel. 2: to get a buzz. Most people I present my wine to, when I tell them I’ve made it myself, ask how much alcohol is in it. For some reason they seem to be curious as to how I did it. Not sure why. If I can’t answer that question, it seems to lessen my credibility as a winemaker. The world is a strange place!

    • From what I recall, it was one of Ed’s articles that said 1 pound of sugar will raise the alcohol potential of a 5 gallon batch by 1%. I take a hydrometer reading when I’ve added 80-90% of the recipe amount of sugar – add more sugar – another reading – etc – until I get to my objective.

  13. Ed, I made a batch of the Banana Berry that was posted several months ago. My starting SG was 1.082. Since I was using previously frozen fruit, I was unsure just how accurate the SG was at the start. After a couple of days in primary the Sg dropped to 1.052 and I added 4 cups sugar as a syrup raising the Sg to 1.060. I like my wines to end between 12-13%. Before sweetening the Sg finished at 0.990. Is it correct to add the 0.008 difference with the added sugar to the starting Sg when figuring the abv? Using these numbers and a calculator app that I found I came up with 13%.

  14. Hello Ed and team,
    Living in tropical zone I have collected good experience in wine making, such as how to make dry and even extra dry fruit wine in temperature 85F -100F, using LALVIN yeast. I have a question regarding calculation of AV. For that I am using factor 129, which comes from my hydrometer instruction. But here some customers of yours use factor 121-122. What is the difference and why? Thank you

  15. This is my first time making wine. I started the wine kit on August 25th. The hydrometer reading states 0% alcohol level. Approximately what level should it be reading at, at this stage?
    Thank you

  16. When I take my hydrometer I just look at the potential alcohol content scale. As a comparison, I purchased some commercially made cider that said 7% alcohol, and that’s what the potential alcohol scale said. Now whenever I measure the cider that I make, I usually can’t get it above 5%, but that’s the way I like it. I recently made some product and it never went up, it went negative on the potential alcohol scale. The blackberry cider that I was trying to make tasted slightly vinegary but not unpleasant. It smelled like it had alcohol in it and I could feel the effect after drinking it. Now I’m totally confused.

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