Hydrometer Guide
Learn how to read and use a hydrometer — the most important measurement tool in homebrewing. Includes a temperature correction calculator.
Temperature Correction Calculator
Hydrometers are calibrated to read accurately at a specific temperature (usually 60°F / 15.6°C). If your sample is at a different temperature, the reading needs correction.
Usually 60°F or 68°F
How to Read a Hydrometer
Collect a Sample
Use a sanitized wine thief or turkey baster to pull a sample from your wort or beer into the hydrometer test jar. Fill it about ¾ full — enough for the hydrometer to float freely.
Insert the Hydrometer
Gently lower the hydrometer into the test jar. Give it a spin to release any air bubbles clinging to the glass — bubbles will make it float higher and give a false reading.
Read at Eye Level
Wait for the hydrometer to stop bobbing. Get your eyes level with the surface of the liquid. Read the scale where the bottom of the meniscus (the curved surface of the liquid) crosses the markings. Not the top of the curve — the bottom.
Record and Correct
Write down the reading and the temperature of the sample. If the sample is not at your hydrometer's calibration temperature, use the correction calculator above to get the true gravity.
Interpreting Your Reading
Water reads 1.000 at calibration temperature. Wort with dissolved sugars reads higher (typically 1.030–1.120 depending on the beer). After fermentation, gravity drops as yeast converts sugar to alcohol. Most beers finish between 1.005–1.020.