What Is Relative Density? Definition, Formula & Examples

Learn what relative density is, its formula, and real-life examples. Simple explanation with easy steps for students.

Relative density (also called specific gravity) is the ratio of the density of a substance to the density of a reference substance — usually water at 4°C.

It's a dimensionless number, which makes it convenient for comparing materials. This post covers the formula, worked examples, and how relative density is measured in the lab using a hydrometer or a density bottle.