What temperature is typically used as a reference when measuring specific gravity?

• A. 0°F
• B. 60°F
• C. 100°F
• D. 32°F

Answer: (B)

Specific gravity is the ratio of a liquid’s density to the density of water at a standard reference temperature. Since density changes with temperature, using a fixed reference temperature lets you compare SG values consistently. In boiler-related practice and many engineering tables, the standard reference is sixty degrees Fahrenheit. That choice keeps water’s density at a well-defined, nearly 1.0 g/cm3 value and allows SG measurements to be used with common tables and without extra temperature corrections. If you measured at another temperature, you’d need to apply a correction to translate the result to the 60°F basis. The other temperatures listed aren’t used as the reference because they don’t provide the same stable, widely adopted baseline.