Science, Tech, Math › Science Molar Volume Definition in Chemistry Share Flipboard Email Print ElementalImaging / Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated August 08, 2019 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. Units 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. Formula Molar volume is calculated as molar mass (M) divided by mass density (ρ): Vm = M / ρ Example The molar volume of an ideal gas at STP is 22.4 L/mol.