Bellwether Brix Hydrometers are calibrated to show the percentage of sucrose by weight at 60°F. The Brix Scale is based on the following: 1° Brix = 1% sucrose by weight at specified temperature (60°F). The data of the National Bureau of Standards are used.

The thermometer scale for Bellwether Hydrometers (w/ Thermometers) is located in the body. All of the thermometers have a range of 30 to 130°F with 1° subdivisions. A correction scale for conversion of readings to 60°F is printed opposite the temperature scale.