Molar Volume Calculator
Calculate the volume occupied by one mole of gas at standard temperature and pressure (STP) or at any custom conditions. Based on the ideal gas law, PV = nRT.
Molar volume is the volume one mole of a substance occupies. For gases, this depends almost entirely on temperature and pressure, not the identity of the gas (as long as it behaves ideally).
At STP (0 degrees C, 1 atm)
One mole of any ideal gas occupies 22.414 L. This is the classic number you memorize in general chemistry.
At Room Temperature (25 degrees C, 1 atm)
Molar volume = RT/P = 0.08206 x 298.15 / 1 = 24.47 L/mol. Warmer gas takes up more space.
The Ideal Gas Law
PV = nRT, where:
- P = pressure in atm
- V = volume in liters
- n = moles of gas
- R = 0.08206 L atm / (mol K)
- T = temperature in Kelvin
Rearranging for molar volume: V/n = RT/P
When Does This Break Down?
The ideal gas law works well at moderate temperatures and low pressures. At very high pressures or very low temperatures, real gases deviate because molecules have actual volume and attract each other. Use the van der Waals equation for those conditions.