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The Essential Guide on How to Use a Hydrometer for Wine: Tips and Tricks


Whether you're an experienced winemaker or a novice just entering the world of winemaking, understanding the tools of the trade is crucial. One such tool is the hydrometer, a simple yet powerful instrument that can unveil a wealth of information about your wine. In this blog post, we will delve into how to use a hydrometer effectively and share some tips and tricks to help you get the most out of this handy device.

Understanding the Hydrometer

A hydrometer is a sealed, hollow, cylindrical glass tube with a weight at the bottom and a graduated scale running up the tube. Think of it as a type of thermometer for your wine, but with even more capabilities. The unique design of the hydrometer allows it to float in liquid, with the weight at the bottom ensuring that it floats upright. As the weight of the displaced liquid equals the weight of the hydrometer, a portion of the scale remains visible above the liquid surface, revealing the density of the liquid compared to pure water.

But why does density matter in winemaking? The answer lies in how sugar and alcohol affect the density of a liquid. When sugar is dissolved in a liquid, it makes the liquid denser. Thus, at the beginning of your winemaking process, the hydrometer can tell you how much sugar is in your wine kit. As fermentation progresses, the sugar is converted into alcohol, which is less dense than water. As a result, the hydrometer can also tell you when fermentation is complete by noting the decrease in density.

How to Use a Hydrometer for Wine

One of the most exciting aspects of using a hydrometer is that it allows you to estimate the alcohol content of your wine. To do this, you need to take a reading at the start of the fermentation process (the 'starting gravity') and another one at the end (the 'finishing gravity'). The change in gravity gives you an idea of how much sugar has been consumed during fermentation. To convert this into an alcohol content, you multiply the change in gravity by 131. For example, if your starting gravity is 1.088 and your finishing gravity is 0.998, the difference is 0.900. Multiplying this by 131 gives an alcohol content of about 11.79% ABV (Alcohol By Volume).

Tips and Tricks for Using the Hydrometer

Now that we've covered the basics, let's delve into some tips and tricks that can help you use a hydrometer more effectively: When you lower the hydrometer into the liquid, give it a gentle spin. This helps to shake off any bubbles clinging to the hydrometer that could affect the reading. If your wine is still fermenting, you need to take the reading quickly before too many bubbles accumulate on the hydrometer. You could also try vigorously shaking your sample in a test jar to remove excess gas. Always extract a sample for testing rather than taking a reading from the primary fermenter. Not only does this provide a better viewing angle for an accurate reading, but it also reduces the amount of oxygen your wine is exposed to, which could affect its quality. Be mindful of the temperature of your wine when taking a specific gravity reading. Most hydrometers are calibrated to take correct readings at 20 degrees Celsius. If your wine is warmer or cooler than this, you'll need to adjust your reading to obtain the true specific gravity. This is because the density of the liquid can change with temperature, which affects the reading.

Taking Care of Your Hydrometer

Like all pieces of winemaking equipment, your hydrometer needs to be cleaned and sanitised regularly. Although hydrometers used to be made solely from glass, modern alternatives, like the Herculometer, are made from durable polycarbonate plastic. While not indestructible, these hydrometers are certainly more resilient and can withstand a few bumps and knocks. Nevertheless, handle with care to ensure your hydrometer serves you well for many batches to come.


Mastering the use of a hydrometer can significantly enhance your winemaking process, providing valuable insights into the sugar content, fermentation progress, and eventual alcohol content of your wine. As with any tool, practice makes perfect. By following the guidelines and tips shared in this post, you'll know how to use a hydrometer for wine. We encourage you to embrace the science of winemaking and view the hydrometer not just as a tool but as a gateway to understanding and improving your wine. Happy winemaking!

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Very interesting, thank you. I usually use the hydrometer when the fermentation stops but I don't really know what I am doing. It is normally around 1.005, after leaving it a few weeks the wine is perfect for me.

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