Hydrometers are instruments that measure the density of liquids. Although hydrometers actually measure density, measurements are commonly expressed in terms of specific gravity (the ratio of density of the substance being measured to the density of water at the same temperature). In precise measurements, the reference may be to pure (double-distilled) water at 4 °C (39.2 °F). In engineering practice, the reference frequently is to pure water at 15.6 °C (60 °F); the value of unity established for water is 1.000. Thus, liquids with a specific gravity less than 1.000 are lighter than water and those greater than 1.000 are heavier than water.

Hydrometers listed are available in plain form (without a thermometer) or combined form (built-in thermometer). Combined form thermometers eliminate the need for a separate temperature measurement.

Select from a range of models that provide specific gravity (g/mL), sugar concentration (Brix scale), alcohol content (Traffe and proof scales), and salt content. Degrees API models are available on special order. Check out the range of plastic hydrometers that are virtually unbreakable. Idea for food and laboratory applications.