A hydrometer, by definition, is a sealed graduated tube containing a weighted bulb, used to
determine the specific gravity or density of a liquid. For home brewing, the purpose of this device
is to measure the amount of sugar in a solution which can be converted into alcohol. Hydrometer
readings should be recorded both before and after fermentation.
Taking a Hydrometer Reading
1. Sanitize all equipment that will come in contact with your wine or beer.
2. Take a sample of the liquid before you add the yeast.
3. Place the sample in a hydrometer test jar. If you have a sampler or pipette,
you do not need to do this as the sampler or pipette doubles as a test jar.
4. Spin the hydrometer to remove any bubbles that might be clinging to it.
5. With the sample at eye level, look to see where the liquid crosses the
6. Write down the reading. This is your starting gravity. Check your recipe to see
what the proper original gravity (OG) range is for your kit.
7. Let the wine or beer ferment completely and then take a reading just before
8. Write that number down. This your final gravity.
9. The equation to figure out the amount of alcohol is this:
(Starting Gravity - Final Gravity) x 131.25.
Example: S.G. 1.050 - F. G. 1.010 = 0.04
0.04 x 131.25 = 5.2% ABV