This ideal gas law calculator solves PV = nRT for pressure, volume, moles, or temperature of an ideal gas.
Physics
Ideal Gas Law Calculator
Solve the ideal gas law for pressure, volume, amount or temperature.
Calculator
About this calculator
Formula notes
PV = nRT with R = 8.314 J/(mol·K). Temperature must be in kelvin: K = °C + 273.15.
Worked examples
- Example: 1 mol at 0 °C (273.15 K) and 1 atm occupies about 22.4 L — the classic molar volume.
- One mole of ideal gas at 101.325 kPa and 273.15 K occupies about 22.414 L when R = 8.314 kPa L/(mol K).
How to use it
- Enter any three of P, V, n, and T.
- Convert Celsius to kelvin before reading results.
- Read the solved fourth variable.
Frequently asked questions
Why must temperature be in kelvin?
The law is proportional to absolute temperature; 0 K is the true zero point.
When does the ideal gas law fail?
At high pressure or low temperature, real gases deviate and need corrections like van der Waals.
Limits and interpretation
- The ideal-gas model becomes less accurate at high pressure, low temperature, near phase changes, or with strongly interacting gases.
- Temperature must be absolute and the chosen gas constant must match pressure and volume units.