3 Reasons Why Your Starting Hydrometer Reading Is Wrong

His Starting Hydrometer Reading Is WrongTaking a starting hydrometer reading is one of the most important things you can do when making homemade wine. This is a reading that is taken with a wine hydrometer before the fermentation has started. It is usually taken at the same time the yeast is added to the wine must.

Having an accurate starting hydrometer reading will not only help you verify that you have an acceptable level of sugar in the wine must, it will allow you to determine the finished wine’s alcohol content. This can be done when the starting reading is compared to the finished reading.

The reading is taken on the Specific Gravity scale. This is a scale based on the weight of water. The weight of the wine is being compared to the weight of water. The more sugar in the wine must the heavier it will be. The more sugar in the wine, the more alcohol the yeast can make.

Keeping in mind its importance, here are the 3 reasons why your starting hydrometer reading is wrong. These are scenarios that I have run across more than once while helping beginning winemakers. In each of these 3 situations the hydrometer reading can be thrown off dramatically.


  1. Shop HydrometersToo Much Water Was Added: This mostly applies to individuals that are making wine from a wine ingredient kit. These kits typically include around 2 to 4 gallons of concentrate to make 6 gallons. The idea is for the winemaker to add water to make up the difference of the 6 gallons. But on rare occasions a beginning winemaker will add a total 6 gallons of water by mistake giving them an 8, 9, 10… gallon batch of wine. This in turn will give them a very low starting sugar reading on their hydrometer.
    1. Sugars Are Not Mixing Evenly: Before taking a starting hydrometer reading it is important to have the sugars completely dissolved and evenly dispersed throughout the wine must. This is regardless if it is from a concentrate or granulated cane sugar. Not doing so can cause your hydrometer sample to be non-representative of the entire batch. The result is an erroneous reading. For example, if the sugars are not completely dissolved and still hanging towards the bottom of the fermenter, the reading you get from a sample take from the top will be very different from the reading you get when taking a sample through a spigot at the bottom of the fermenter.
  1. Hydrometer Jar Not Being Used: One of the requirements for taking a starting hydrometer reading, is the hydrometer needs to be able to float. If the container being used to hold the sample isn’t tall enough, the hydrometer will sit on the bottom. Again, this will give you a wrong reading. This normally happens when the winemaker is trying to use the plastic tube the hydrometer came in to take the reading. This is something I strongly urge against for the simple fact it is not always tall enough to float the hydrometer. Instead, you should be using a hydrometer jar that is designed specifically for this purpose. It is more than tall enough and has a sturdy base so you can keep the wine sample steady and vertical while taking the reading.Shop Hydrometer Jars


These are by far the 3 most common reasons. If you think you have a starting hydrometer reading that is wrong, it is probably because of one of these three. There are other reasons as to why a hydrometer reading might not be completely accurate, such as not having your eye-level even with the surface of the wine, but these are the 3 “big ones”. Avoid doing them and you’ll be sure to have dependable readings.
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.


9 thoughts on “3 Reasons Why Your Starting Hydrometer Reading Is Wrong

  1. I am 24 days in my 1st wine making attempt with a juice concentrate from a kit. I have used the hydrometer 3 times putting it straight into the fermenter. The readings are the same each time right around 1050. Is there something I may be doing wrong? I followed all instructions to a tee.

    • Dean, it doesn’t sound like you are having a problem with the hydrometer reading itself but may be experiencing a stuck or sluggish fermentation. I am providing you with the link to our article on the most common causes of fermentation failure. See if any of the reasons may apply to your situation.

      Top Ten Reasons For Fermentation Failure.

  2. I am new to wine making and noticed that my hydro readings read lower than what would be expected from the amount of sugar I put in. (When I tested my hydrometer it read about .046 to a gallon of water with one pound of sugar in it.) I suspect the sugar was not fully dissolved despite prolonged agitation and stirring. Is there a technique you recommend for making sure it is?


    • Tom, to ensure your sugar dissolves properly, we recommend dissolving it in warm water, let the water cool and then add it to the fermentation vessel.

  3. How do you compensate for water that is added after 1st reading at the beginning and before last reading before bottling?? Should a dilution adjustment be applied to one of the SG readings?
    I ask because often I will have up to 25% disagreement between SG calculations and Vinometer readings (even with a batch I have not diluted during the process). I know Vinometer will be inaccurate with higher alcohol wines, so I take Vinometer readings straight and diluted 50% with distilled water.

  4. No one has mentioned that Hydrometers come in different Temperature ratings. You are suppose to take the sample at that stated Temp. and they come with a compensation chart. I was sure you would have had this on your list.
    I used to use the container it came in, it was tall enough for sure but narrow and it always ” stuck” to the glass on the sides even though I would spin it ( no one mentioned this trick either) when I put it in the container.
    I bought a good Hydrometer testing container later on as I got better and never regretted it. Now it never sticks to the side .

  5. Hi,

    I freeze my fruit first to make them go mushy as recommended on this website, I then bash them a bit when making the must.

    My question is, if I take my hydrometer reading of my solution before adding the yeast, will some of the available sugar not be locked up in the cells of the fruit and not in the solution? This sugar then surely becomes available as the yeast breaks the fruit down during the primary fermentation….

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