How to Use a Hydrometer

A picture of a hydrometer

A hydrometer is perhaps the most essential piece of measuring & testing equipment in any home brewery. Used it at every stage of brewing to keep up with the health and progress of your homebrew.  

  Many hydrometers (from features three scales–specific gravity, potential alcohol and brix–and is handy for both brewing and winemaking. It measures 9 inches long and comes with complete, detailed instructions for proper use. 

As more and more sugar gets converted to ethanol (which is less dense than water), the hydrometer sinks further and further into the fluid. Water has a specific gravity of 1.0. Beers usually have a final gravity of between 1.005 and 1.015 (although there are many that finish higher). The higher that the beer’s finishing gravity, the more sugars are left in the beer and the sweeter it will taste. Beers that finish around 1.005 will be perceived as being “dry” because they have very little residual sugars left. This is just one tool you can use. Use it to find problems in mashing, boiling, and fermentation.

How to Read Your Beer Hydrometer

A diagram for reading the meniscus on a hydrometer

Pour your sample into a clear cylinder that is dry or has been well rinsed with your sample

  1. Be sure your sample is well mixed prior to testing
  2. Immerse the hydrometer in the solution to a point slightly below the point where it naturally floats. Spin it to free it from any clinging bubbles which might buoy the instrument. Make sure the liquid is still.
  3. Measure the temperature of the sample. Ideally, the sample’s temperature will be equal to the calibration temperature of the hydrometer, generally 60°F. If you cannot avoid temperature differences, use the chart below to adjust the reading.
  4. Take your reading at eye level. Read at the point where the surface of the liquid crosses the hydrometer, at the bottom of the meniscus (see the example above).

Download this temperature correction table from Thermco Products, Inc. in .pdf form.

How to Calibrate Your Beer Hydrometer

Calibrate by measuring distilled water at the calibration temperature (usually 60° or 68°F) and apply the correction factor to all readings. When reading specific gravities at temperatures other than the calibration temperature, such as a post-boil gravity at 120°F, use the chart below:

Video: by NorthernBrewerTV on YouTube

Hydrometer Temperature
Correction Table

Degrees FahrenheitAdjustment to
40Subtract .002
50Subtract .001
70Add .001
80Add .002
90Add .004
100Add .005
110Add .007
120Add .008
130Add .010
140Add .013
150Add .015

Purchase your hydrometers at

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