Ideal Gas Law Calculator
Solve PV equals nRT for pressure, volume, amount or absolute temperature with fixed SI units.
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Solve any variable in the ideal gas law
Select pressure, volume, amount or temperature as the unknown, then enter the other three quantities in SI units. The calculator uses PV equals nRT with the displayed universal gas constant and returns the complete state. Explicit pascals, cubic meters, moles and kelvin labels reduce the unit ambiguity that often causes otherwise correct formulas to fail.
Recognize where a real gas departs from the model
The ideal gas law is an approximation that is often most useful at modest pressure and away from condensation. High pressure, low temperature, mixtures and phase changes can require compressibility data or a real-gas equation. Kelvin temperature must remain positive. Convert gauge pressure to absolute pressure when the physical problem requires an absolute thermodynamic state.
Frequently asked questions
Which gas constant is used?
The tool uses 8.31446261815324 joules per mole kelvin.
Can I enter Celsius directly?
No. Convert temperature to kelvin before calculation.
Should pressure be absolute or gauge?
The ideal gas law uses absolute pressure.