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Ideal gas law, PV = nRT

Pressure, volume, amount of substance or temperature of an ideal gas from PV = nRT, with unit conversion.

Parameters

Known quantities
Pressure (P)
Volume (V)
Amount of substance (n)
Temperature (T)

Result

Awaiting the quantities required for the calculation.

Assumptions and warnings

  • This domain calculates using the ideal-gas model: an approximation that neglects molecular volume and intermolecular interactions.

Calculation, assumptions and sources

Provisional · Physical model · 1 source · reviewed on 1 August 2026

OverviewThree of pressure P, volume V, amount of substance n and temperature T give the fourth from PV = nRT, in SI units.

Three of pressure P, volume V, amount of substance n and temperature T give the fourth from PV = nRT, in SI units.

Method & formulasP × V = n × R × T
P × V = n × R × TR = 8.31446261815324 J·mol⁻¹·K⁻¹

The ideal gas constant R is exact since the 2019 redefinition of the SI.

P
pressure of the gas.
V
volume occupied by the gas.
n
amount of substance of gas, in moles.
T
absolute temperature, in kelvins.
R
ideal gas constant.
AssumptionsIdeal gas: point particles with no interactions.
  • Ideal gas: point particles with no interactions.
Validity domain4 validity limits; the calculation refuses values outside 4 of them

The model becomes inaccurate at high pressure and near liquefaction, where a real equation of state (van der Waals) is needed.

  • T ≥ 0physical · refusal

    Absolute temperature cannot be negative or zero (absolute zero).

    Instead · Check the unit: a negative °C or °F temperature is converted to kelvins before this check.

  • P ≥ 0physical · refusal

    Pressure cannot be negative.

    Instead · Check the sign of the pressure.

  • V ≥ 0physical · refusal

    Volume cannot be negative.

    Instead · Check the sign of the volume.

  • n ≥ 0physical · refusal

    Amount of substance cannot be negative.

    Instead · Check the sign of the amount of substance.

ExampleOne mole of gas at 0 °C (273.15 K) under 1 atm (101,325 Pa): V = nRT / P = 1 × 8.31446261815324 × 273.15 / 101,325 ≈ 0.02241 m³, i.e.

One mole of gas at 0 °C (273.15 K) under 1 atm (101,325 Pa): V = nRT / P = 1 × 8.31446261815324 × 273.15 / 101,325 ≈ 0.02241 m³, i.e. 22.41 L, the standard molar volume.

SourcesCODATA (Committee on Data of the International Science Council)

  1. CODATA (Committee on Data of the International Science Council), CODATA Internationally Recommended 2022 Values of the Fundamental Physical Constants, 2022.

    Location: molar gas constant · accessed 2026-07-31

Scientific validationProvisional, reviewed on 1 August 2026

Provisional · Sources and assumptions are provided; the documentary review is incomplete.

Physical model. The result follows the significant figures of the least precise input.

revision 1 · reviewed on 1 August 2026

Revision log

  1. revision 1 · 2026-08-01 · source update

    Ajout de la source de R, des hypothèses et du domaine de validité.

    Aucun changement de résultat : R est inchangée.