Relative density

Ratio of two densities

Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass divided by volume) of a substance to the density of a given reference material. The relative density of solids and liquids is nearly always measured with respect to water at its densest (at 4 °C or 39.2 °F); for gases, the reference is air at room temperature (25 °C or 77.0 °F). The term "relative density" (abbreviated r.d.

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