Starting And Final Specific Gravity Readings For Wine

Taking Final Specific Gravity ReadingI am in the process of making my first batch of Scuppernong Wine. The SG [specific gravity] at the beginning was 1.116… The process has been going on for about 8 weeks now. The SG now is 1.030… I still see activity. What should the final specific gravity reading be when the wine is complete?

Name: Charles P.
State: South Carolina
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Hello Charles,

To answer your question, you should expect a final specific gravity for wine somewhere between .992 and .996 on your hydrometer.

Your starting specific gravity reading was a little high, so your wine yeast has a lot of work to do. Normally you would want a starting specific gravity between 1.070 and 1.100 for wine. Yours was 1.116. This may be more than the wine yeast can handle.

 

There are two reasons for this:

  1. Shop HydrometersSugar acts as a preservative. If the concentrate of sugar becomes too high, it can actually interfere with the wine yeast from even starting. Your fermentation started, so obviously this is not an issue for this fermentation.
  1. Wine yeast has a limited tolerance to alcohol. As the alcohol level rises in the wine must, the wine yeast finds it harder and harder to ferment, sometimes to the point of not being able to ferment at all. This would be known as a stuck fermentation.

 

Your starting potential alcohol level was between 15% and 16%. A majority of wine yeast will have a hard time fermenting to this level of alcohol.

My guess is that your fermentation will become very slow as it ferments the last few percentage points of sugar. If this is the case, just be patient and give it plenty of time to do its thing. As long as you can see some slight progress, you are okay.

However, depending on the wine yeast you used, the fermentation may not be able to finish at all – a stuck fermentation. If this is the case, you may be forced into a situation to where you need to dilute the wine must with water to cut its alcohol level. This will help the yeast to start up again and finish the fermentation.

Shop Hydrometer JarsSince the starting specific gravity for your wine was so high, I would recommend that you also take a look at the Top 10 Reasons For Fermentation Failure. By doing this you may discover other things that can be done to help the fermentation along and get the final specific gravity for your wine where it needs to be.

Happy Winemaking,
Ed Kraus
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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.

16 thoughts on “Starting And Final Specific Gravity Readings For Wine

  1. What would happen if I just added a camden tab and potassium sorbate to stop the fermentation at that point? Would it have a more fruity taste because there is residual sugar?

  2. Jan, you have to use something called the Pearson’s Square. It’s a visual math tool that helps you to determine the ratio you need of two liquids to achieve a particular reading. In your case specific, SG with wine must and water to be blended. You can find more on the Pearson’s Square about half way down on this article on blending wines. Hint: think of water as one of the wines being blended: http://www.eckraus.com/wine-making-blending/

  3. Bob, more than half the time this works, but it is far from a guaranteed stop. Most of it has to do with how many yeast cells are still floating in the wine. If it doesn’t work the cost can be great. Your wine could end up fermenting in the bottles; pushing the corks out and making a mess. And worse yet, if the corks don’t give the wine bottles could start exploding. You can find more on this at the following blog post:

    How To Stop A Fermentation
    http://www.eckraus.com/wine-making-stop-fermentation/

  4. Hello
    I have a 6 gallon carboy that I had to restart the fermentation because it seemed to have stopped.
    I used your recommendation on how to restart.
    It has started bubbling again very slow it’s been a 10 days and the specific gravity is still at 1.040 and has not moved.
    Should I see SG movement in that amount of time?

    • Rob, if you are seeing fermentation activity then you should see movement in the hydrometer reading. You can check your hydrometer in water to make sure that you are getting a correct reading. If it is still stuck, take a look at the following article to see if something else could be causing a stuck fermentation.

      Reasons For Stuck Fermentation
      http://www.eckraus.com/wine-making-failure

  5. Ed, I started a Cabernet Sauvignon and after adding the yeast the SG registered 70.
    Do I need to add more water to bring it closer to 1.07-1.08?

    • Matthew, knowing the specific gravity that you determine with a wine hydrometer is important to the success of your fermentations and winemaking in general. Without a wine hydrometer, it’s much more difficult to determine the sugar level in your wine must or your wine, thus making it even more difficult to know how your fermentation is progressing and if there are any unexpected adjustments you need to make. Wine making using a hydrometer; monitoring the specific gravity of your must, you’ll be ready when an unexpected change occurs requiring your attention and adjustments, and you’ll be able to determine how much potential alcohol the wine you are creating will be and you can adjust accordingly if need be. The hydrometer reading is the only way to know for sure that the fermentation has completed or if it becomes stuck.

  6. My wine sg was 1050 .the second fermentation is almost finished but it’s stuck at 1028 this is my first batch of wine I need help

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