Specific gravity is a dimensionless quantity. In general the specific gravity of any substance is defined concerning water at 4⁰C. Specific gravity has no units because its a ratio of density divided by density so all units cancel out.
Because it is the ratio of.
Specific Gravity of gases is normally calculated with reference to air - and defined as the ratio of the density of the gas to the density of the air - at a specified temperature and pressure. In general the specific gravity of any substance is defined concerning water at 4⁰C. Since the specific gravity formula consists of one density divided by another the. The Specific Gravity can be calculated as.