Ideal Gas Law Calculator
PV = nRT, solving for whichever term is missing.
Work out Ideal Gas Law. PV = nRT, solving for whichever term is missing. Shows the working, not just the answer.
Real gases depart from this at high pressure and near their condensation point, where molecular volume and intermolecular attraction stop being negligible. For everyday conditions the error is under a percent; near liquefaction it is large.
Volume (m³)
0.02241
22.414 litres · 273.15 K
PV = nRT, with R exactly 8.31446261815324 J/(mol·K) — a defined constant since the 2019 SI redefinition rather than a measured one. Temperature must be absolute: the equation uses kelvin, and using Celsius directly is the single commonest error here. One mole at 0 °C and one atmosphere occupies 22.41 litres regardless of which gas it is.
How the Ideal Gas Law Calculator works
PV = nRT, with R exactly 8.31446261815324 J/(mol·K) — a defined constant since the 2019 SI redefinition rather than a measured one. Temperature must be absolute, and using Celsius directly is the commonest error here.
Also known as: pv = nrt calculator · gas law calculator · molar volume calculator · ideal gas equation
Frequently asked questions
What is the ideal gas law?
PV = nRT — pressure times volume equals moles times the gas constant times absolute temperature. It relates all four quantities, so any three give the fourth.
What volume does one mole of gas occupy?
22.41 litres at 0 °C and one atmosphere, regardless of which gas it is. That result — equal volumes of any gas hold equal numbers of molecules — is Avogadro's law.
Why must I use kelvin?
Because the equation is proportional to absolute temperature. Using Celsius makes 0° into zero, which would imply a gas has no volume at freezing point. Add 273.15.
When does the ideal gas law break down?
At high pressure and near condensation, where molecular volume and intermolecular attraction stop being negligible. For everyday conditions the error is under a percent.
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