What is the specific gravity of mercury?

The specific gravity of mercury is 13.6. Specific gravity is also called relative density and is the ratio of the density of one substance to that of a standard substance such as water. Density is an object's mass per unit volume.

Mass is a measure of the amount of matter in a substance (informally weight, although weight implies the presence of gravity). The standard substance most commonly used to compare for specific gravity is water at 4 degrees Celsius, which has a density of 1 kilogram per liter. Specific gravity has no dimension because it is a ratio of two quantities with the same dimension (mass per unit volume).