Molar Gas Volume Calculator (STP)
Convert moles of any ideal gas into volume at standard temperature and pressure (STP), using either the traditional or the current IUPAC definition of STP.
What molar gas volume means
According to Avogadro’s law, equal volumes of any ideal gas at the same temperature and pressure contain the same number of moles. At standard temperature and pressure (STP), one mole of any ideal gas occupies the same fixed volume, regardless of what the gas is.
The formula used
This calculator uses V = n × Vm, where n is the number of moles and Vm is the molar volume at STP. Two common STP conventions are supported: the traditional definition (0°C and 1 atm), where Vm = 22.414 L/mol, and the current IUPAC definition (0°C and 100 kPa), where Vm = 22.711 L/mol. Both are derived from the ideal gas law, PV = nRT.
- Choose the STP definition that matches your textbook or exam.
- Results are shown in both liters and milliliters.
This calculator assumes ideal gas behavior, which is a very close approximation for most real gases at STP and is standard for introductory chemistry coursework. It is intended for general chemistry education purposes.