How to use this calculator
- Select pressure, volume, amount, or temperature as the unknown.
- Enter the other three values and select each unit.
- Calculate and read the result in the unit selected for the unknown.
Formula and variables
PV = nRT
| Symbol | Meaning | Unit |
|---|---|---|
| P | pressure | Pa |
| V | volume | m3 |
| n | amount | mol |
| T | temperature | K |
Worked example
One mole at 1 atm and 273.15 K occupies about 0.022414 m3 under the ideal model.
Interpretation
The ideal-gas result is a model calculation; real gases deviate depending on pressure, temperature, and intermolecular behavior.
Common mistakes
- Temperature is converted to Kelvin before calculation.
- Do not mix units without selecting each unit explicitly.
Frequently asked questions
Which gas constant does the calculator use?
It uses the CODATA molar gas constant and normalizes the entered units before calculation.
Can I enter Celsius or Fahrenheit?
Yes. The calculator converts the temperature to Kelvin before it applies PV = nRT.
When does the ideal gas law become inaccurate?
Deviation increases near condensation and at high pressure, where intermolecular effects become important.
Can I use scientific notation?
Yes. Enter values such as 6.022e23 or 1.0e-6 in a numeric field.
How should I round the result?
Keep extra digits during the calculation. Round the final result to the precision required by your data.