Fuhyo (hydrometer)

A fuhyo (hydrometer; 浮ひょう) is an instrument based on Archimedes' principle that is used to measure the specific gravity of a liquid. It plays an especially important role in sake production. In quality control and throughout the brewing process, hydrometers are used to measure indicators such as alcohol content, the sake meter value (SMV, or nihonshudo), and Baume degrees. These measurements make it possible to accurately determine the purity, alcohol content, and sugar content of the sake. They provide important data for assessing the characteristics of a sake and for making adjustments during brewing.