Ideal Gas Law Calculator
Solve PV = nRT for pressure, volume, amount of gas or absolute temperature. Enter any three variables and use metric or US customary units.
Ideal gas law formulas
PV = nRT
- Pressure: P = nRT / V
- Volume: V = nRT / P
- Amount: n = PV / RT
- Temperature: T = PV / nR
This calculator uses R = 8.31446261815324 Pa·m³·mol⁻¹·K⁻¹ and the exact Avogadro constant, 6.02214076×10²³ mol⁻¹. All entries are converted to SI before calculation.
How to use the calculator
- Select the variable to solve.
- Enter the other three values and select each unit.
- Use absolute pressure. Add local atmospheric pressure to gauge pressure when necessary.
- Select Calculate and review the answer, SI equivalents, molar volume, concentration and equation check.
Checked examples
| Known values | Solve for | Result |
|---|---|---|
| n = 1 mol, V = 22.414 L, T = 273.15 K | Pressure | ≈ 1.000 atm |
| P = 1 atm, n = 2 mol, T = 25 °C | Volume | ≈ 48.93 L |
| P = 200 kPa, V = 5 L, T = 300 K | Amount | ≈ 0.4009 mol |
| P = 1 atm, V = 10 L, n = 0.5 mol | Temperature | ≈ 243.73 K |
| n = 1 mol, V = 24 L, T = 25 °C | Pressure | ≈ 1.019 atm |
| P = 5 bar, n = 1000 mol, T = 400 K | Volume | ≈ 6.652 m³ |
| P = 14.6959 psi, V = 1 ft³, T = 70 °F | Amount | ≈ 1.173 mol |
| n = 1 mmol | Particles | ≈ 6.02214×10²⁰ particles |
Scope and limits
- The ideal gas law assumes point particles with negligible intermolecular forces. Real gases can deviate at high pressure, low temperature or near phase changes.
- Use absolute pressure. Gauge pressure entered directly produces an incorrect result.
- Temperature must be greater than 0 K (−273.15 °C or −459.67 °F).
- Inputs must be finite positive values no greater than 10200. Results outside JavaScript’s finite numeric range are rejected.
- The particle estimate treats n as the number of moles of specified entities; it does not infer molecular composition or mass.