Molar Volume Calculator
Find the volume occupied by one mole of a gas using the ideal gas law, or convert a sample’s mass and molar mass into total gas volume.
What This Calculator Does
The molar volume of a gas is the space that one mole of that gas occupies at a given temperature and pressure. Under the ideal gas approximation, molar volume does not depend on which gas it is — only on temperature and pressure — which is why one mole of any ideal gas at standard temperature and pressure (STP: 0°C and 1 atm) occupies about 22.4 liters.
The Formula
This calculator rearranges the ideal gas law, PV = nRT, to solve for volume per mole: Vm = RT ÷ P, where R is the ideal gas constant (0.0820574 L·atm/(mol·K)), T is absolute temperature in kelvin, and P is pressure in atmospheres. In sample mode, the number of moles is first found from moles = mass ÷ molar mass, then multiplied by the molar volume to give the total volume of the sample.
A Few Notes
- This uses the ideal gas model, which is very accurate for most gases at normal pressures and moderate temperatures but becomes less precise at very high pressure or very low temperature, where real-gas effects matter.
- Temperature is automatically converted to kelvin internally for the calculation.
- This tool is intended for general chemistry education and planning purposes, not for precision industrial or laboratory gas measurements.