Ideal Gas Law Calculator
Solve for any one variable in the Ideal Gas Law equation: PV = nRT. Enter any three known values and leave the unknown field empty.
Enter three values and leave one blank to solve for it.
Formula
PV = nRT
- P = Absolute pressure [Pa]
- V = Volume [m³]
- n = Amount of substance [mol]
- R = Universal gas constant = 8.314462618 J/(mol·K)
- T = Absolute temperature [K]
Rearrangements:
- P = nRT / V
- V = nRT / P
- n = PV / RT
- T = PV / nR
Assumptions & References
- The gas behaves as an ideal gas: molecules have negligible volume and no intermolecular forces.
- All inputs must use SI base units: Pascals (Pa), cubic metres (m³), moles (mol), and Kelvin (K).
- Temperature must be in absolute Kelvin (K = °C + 273.15). Negative Kelvin values are physically impossible.
- The gas constant R = 8.314462618 J/(mol·K) is the 2018 CODATA recommended value (exact since 2019 SI redefinition).
- This model is most accurate at low pressures and high temperatures. At high pressures or near condensation, use the van der Waals equation instead.
- Reference: NIST Chemistry WebBook — Ideal Gas Law, and IUPAC 2019 SI redefinition of the mole.