Molar Volume Definition in Chemistry

Glassware containing blue liquid

ElementalImaging / Getty Images

Molar volume is the volume of one mole of a substance at a specified pressure and temperature. It is commonly denoted by the symbol Vm.


The SI unit of molar volume is cubic meters per mole (m3/mol). However, because that is such a large volume, other units are usually used. Cubic centimeters per mole (cm3/mol) is used for solids and liquids. Cubic decimeters per mole (dm3/mol) may be used for gases.


Molar volume is calculated as molar mass (M) divided by mass density (ρ):

Vm = M / ρ


The molar volume of an ideal gas at STP is 22.4 L/mol.