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How to Read a Hydrometer

Reading a Hydrometer
Start making (really) good beer!

Making good beer is not only about good ingredients. Sanitizing, racking to a secondary, and taking hydrometer readings all make a better product. Of these, the hydrometer reading is most neglected by home brewers. I am not sure if it is the thought that it is difficult or simply not a useful resource. Either way, not taking a hydrometer reading is a mistake!

What is a hydrometer? By definition it is a sealed graduated tube containing a weighted bulb, used to determine the specific gravity or density of a liquid. For our hobby, the purpose of this device is to measure amounts of sugar in a solution which can be converted into alcohol(now I have your attention). Hydrometer readings should be recorded both before and after fermentation.

How to Read a Hydrometer
You will need to start with a beer/wine hydrometer and some type of test jar. The test jar should be long enough for the hydrometer with adequate room allowing it to float without restraint. The test jar should be filled with enough of your product to permit the hydrometer to float. Samples should correspond with the temperature listed on your hydrometer. This is usually 60 or 70 F for most homebrew hydrometers. Once you have filled the test jar with enough wort, gently lower your hydrometer into the sample. The hydrometer will float with a reading across the top of your sample.

1. Fill Test Jar with sample to be tested.
2. Put Hydrometer in, bulb end down, and spin slowly.
Note: watch for overflow of the test jar

3. Assure the hydrometer is not in contact with the sides of the test jar.
4. Discard the sample - DO NOT ADD TO BEER.

What you have is your original or starting gravity. Record this along with your recipe as it is every bit as important to recreate this beer, wine, or mead. In a week or two your fermentation should be complete. It is now time to take a final hydrometer reading often referred to as your final gravity. Follow the hydrometer instructions as listed above for your final gravity and record this along with your original gravity.

Now what?
The original and final gravities of your beverage have many uses. Alcohol content, grain efficiency, or recipe calculations are a few reasons to use this great resource. Below you will find a quick formula for alcohol calculation. If you have other questions, please shoot us an e-mail!

ABV% Calculator
(OG - FG) x 131.25 = ABV%
(___* - ___**) x 131.25 = ___%

*Original Gravity - **Final Gravity

Jason Smith
Adventures in Homebrewing