what is the specific gravity

Specific gravity, also known as relative density, is a dimensionless quantity that is defined as the ratio of the density of a substance to the density of a given reference material. The reference material is usually water at a specified temperature and pressure, and the specific gravity is expressed as a ratio without units. Specific gravity is commonly used in industry as a simple means of obtaining information about the concentration of solutions of various materials such as brines, must weight, and acids. It is also used in various fields such as gemology, chemistry, and auto mechanics. Specific gravity can be calculated by dividing the density of a material by the density of water at a specified temperature and pressure. The ease with which specific gravity can be precisely determined leads to its widespread use in chemical science and technology.