Ideal gas law, PV = nRT
P × V = n × R × T
Enter three quantities among pressure (P), volume (V), amount of substance (n) and temperature (T): the tool calculates the fourth from the ideal gas law PV = nRT, converting each quantity to SI units.
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.
Scientific dossier
What the tool computes, what it assumes, where it stops being valid, and where its data comes from.
Method & formulasP × V = n × R × T
P × V = n × R × T
R = 8.31446261815324 J·mol⁻¹·K⁻¹
The ideal gas law relates the pressure, volume, amount of substance and absolute temperature of a gas. The 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, calculations are carried out in kelvins.
- R
- · ideal gas constant, 8.31446261815324 J·mol⁻¹·K⁻¹.
AssumptionsThe gas is ideal: point particles with no interactions.
- The gas is ideal: point particles with no interactions. A real gas deviates, especially at high pressure or low temperature.
Validity domain4 bounds declared, 4 blocking
The ideal gas model neglects the intrinsic volume of molecules and the interactions between them: it becomes inaccurate at high pressure and near the liquefaction point, where a real equation of state (van der Waals) is needed. Temperature must always be an absolute temperature, the tool automatically converts Celsius and Fahrenheit degrees to kelvins, and rejects any value below absolute zero.
T ≥ 0physical · refusal
Absolute temperature cannot be negative or zero (absolute zero).
Instead · Check the chosen unit: a negative °C or °F reading is normal, but it is converted to kelvin before this check.
P ≥ 0physical · refusal
Pressure cannot be negative.
Instead · Check the sign of the entered pressure value.
V ≥ 0physical · refusal
Volume cannot be negative.
Instead · Check the sign of the entered volume value.
n ≥ 0physical · refusal
Amount of substance cannot be negative.
Instead · Check the sign of the entered amount-of-substance value.
ExampleOne mole of gas at 0 °C (273.
One mole of gas at 0 °C (273.15 K) under 1 atm (101,325 Pa) occupies about 22.41 L: V = nRT / P = 1 × 8.31446261815324 × 273.15 / 101,325 ≈ 0.02241 m³. This is the standard molar volume.
SourcesCODATA (Committee on Data of the International Science Council)
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 · revision 1 · reviewed 2026-08-01
Provisional · Sources and assumptions are declared; the full documentary review is still pending.
Physical model. The result follows the significant figures of the least precise input.
revision 1 · reviewed 2026-08-01
Revision log
revision 1 · 2026-08-01 · source update
Bloc scientifique renseigné : source de R, hypothèses et domaine de validité déclarés.
Aucun changement de résultat, R.value est identique à la valeur déjà affichée.