Ideal Gas Law Calculator (PV = nRT)
Solve PV = nRT for any unknown. Enter three of pressure (Pa), volume (m³), moles and temperature (K) to find the fourth. Uses R = 8.314 J/mol·K.
How to use this tool
- Enter pressure (p), volume (v), amount (n) and temperature (t) in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your pressure and the full breakdown beneath it.
The ideal gas law combines Boyle's, Charles's and Avogadro's laws: PV = nRT, where P is pressure (Pa), V is volume (m³), n is amount (mol), R = 8.314 J/mol·K, and T is temperature (K). Convert Celsius to Kelvin: T(K) = T(°C) + 273.15.
Frequently asked questions
- What is standard temperature and pressure (STP)?
- STP is 273.15 K (0 °C) and 101,325 Pa (1 atm). One mole of ideal gas occupies 22.414 litres at STP.
- When does the ideal gas law break down?
- At very high pressures or very low temperatures, intermolecular forces matter and you need the van der Waals equation or other corrections.