What is the specific gravity of pure water?

The specific gravity of pure water is defined as 1.0 under standard conditions, which typically means at a temperature of 4 degrees Celsius and at sea level. Specific gravity is a dimensionless quantity that compares the density of a substance to the density of a reference substance, which is commonly water for liquids. Since pure water has a density of approximately 1 gram per cubic centimeter (g/cm³), this means its specific gravity is also calculated to be 1.0.

This measurement is significant in various applications, including brewing, where understanding the specific gravity of liquids can help assess sugar content, fermentation progress, and overall brewing science. The other options present specific gravities that do not accurately represent pure water—0.5 indicates a much lighter substance, while 1.5 and 2.0 suggest increasingly denser materials, all of which deviate from the characteristics of water.