About this calculator
Choose what to solve for, enter the other three values, and get the answer from PV = nRT.
Use pressure in kPa, volume in litres, the amount of gas in moles and temperature in kelvin or Celsius. The result is also shown in atmospheres, bar, psi and other units where useful.
Worked examples
Real numbers, worked out by the same calculator. Press “Use these numbers” to try one above.
Pressure of 1 mol in 22.414 L at 273.15 K
- Pressure
- 101.324862 kPa
- In atmospheres
- 0.999999 atm
- In bar
- 1.013249 bar
- In psi
- 14.695929 psi
For an ideal gas, PV = nRT gives pressure = 101.324862 kPa.
Show the working
- The ideal gas law is PV = nRT, with R = 8.314462618 kPa·L/(mol·K) when pressure is in kPa and volume in litres.
- Check: P × V = 101.324862 × 22.414 = 2,271.095464, and n × R × T = 1 × 8.3145 × 273.15 = 2,271.095464.
Volume of 1 mol at 101.325 kPa and 25 °C
- Volume
- 24.465404 L
- In cubic metres
- 0.024465 m³
For an ideal gas, PV = nRT gives volume = 24.465404 L.
Show the working
- The ideal gas law is PV = nRT, with R = 8.314462618 kPa·L/(mol·K) when pressure is in kPa and volume in litres.
- Check: P × V = 101.325 × 24.465404 = 2,478.95703, and n × R × T = 1 × 8.3145 × 298.15 = 2,478.95703.
Moles in 10 L at 200 kPa and 20 °C
- Amount of gas
- 0.820552 mol
For an ideal gas, PV = nRT gives amount of gas = 0.820552 mol.
Show the working
- The ideal gas law is PV = nRT, with R = 8.314462618 kPa·L/(mol·K) when pressure is in kPa and volume in litres.
- Check: P × V = 200 × 10 = 2,000, and n × R × T = 0.820552 × 8.3145 × 293.15 = 2,000.
The ideal gas law
PV = nRT: pressure × volume = amount of gas × the gas constant × temperature. With pressure in kPa and volume in litres, R = 8.314462618. Temperature must be in kelvin (Celsius + 273.15), which the calculator handles.
Standard conditions
One mole of an ideal gas at 0 °C (273.15 K) and 101.325 kPa occupies 22.414 litres. At 25 °C it occupies about 24.465 litres. The calculator reproduces both figures.
When the law works
Real gases behave like an ideal gas at low pressure and high temperature. At high pressures or near the point where a gas turns to liquid, the law becomes less accurate.
Frequently asked questions
What is the ideal gas constant?
R = 8.314462618 J/(mol·K), which is the same number in kPa·L/(mol·K).
Why must temperature be in kelvin?
The law relates pressure and volume to the absolute temperature, so zero must mean no thermal energy: 0 K.
What is the volume of one mole of gas?
22.414 L at 0 °C and 1 atm, or about 24.465 L at 25 °C.
Does it work for real gases?
Approximately, at modest pressures and temperatures well above the boiling point.
Formulas tested against hand-worked answers. Last reviewed 29 September 2026. These calculators do arithmetic only; they are not financial, tax or legal advice.