Best Test Jars for Homebrew Hydrometer Samples (2026)

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A test jar is the tall cylinder that holds a sample so your hydrometer can float freely and give a clean reading. Height is the first thing to check, because the jar has to be deep enough for the hydrometer to float without bottoming out or bumping the sides. Plastic jars shrug off drops and suit a busy bench, while glass gives a clearer view of the scale and resists scratching over time. A wide, stable base keeps the whole thing from tipping when you drop a sample in, which saves both your beer and your hydrometer. Any brewer using a hydrometer needs a test jar to go with it, since taking readings in the fermenter is awkward and risks contamination. It pairs directly with your hydrometer, and a size matched to that tool avoids the frustration of a float that will not settle. Choose plastic if you tend to knock things over and glass if you value a crisp view of the reading. Sanitize it like any other gear if you plan to return the sample, though many brewers simply taste the sample and pour it away.