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Ideal Gas Law Calculator
Solve PV = nRT for any one variable, with the gas constant in several unit systems and a note on real gas deviation.
Solve the ideal gas law
Result: —
Equation: —
Gas constant: —
Status: —
How to use the Ideal Gas Law Calculator
- Choose which variable you want to solve for and the unit system.
- Fill in the other three values, such as pressure, volume and temperature.
- Read the answer with the rearranged equation and the gas constant used.
Features
- Solves for pressure, volume, moles or temperature
- Four unit systems with the matching gas constant
- Shows the rearranged equation with values inserted
- Notes when real gases deviate from ideal behaviour
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Frequently Asked Questions
Common questions about the free online ideal gas law calculator.
Choose the variable you want to find, pick a unit system, then fill in the other three values
and read the answer below.
Any one of the four: pressure, volume, amount in moles or temperature. The other three are
taken from the input boxes.
Pascals with cubic metres, atmospheres with litres, kilopascals with litres and torr with
litres, each with the correct gas constant.
The panel shows the exact value in the chosen units, such as 8.314462618 for pascals and
cubic metres per mole per kelvin.
The ideal gas law is proportional to absolute temperature, so kelvin is required. The tool
rejects zero or negative values.
At high pressure and low temperature the molecules attract each other and take up volume, so
the compressibility factor moves away from one.
No. Every calculation runs in your browser and nothing you type is sent anywhere.
Yes. It is completely free, needs no account and there are no limits on how many times you
use it.
Last updated: October 10, 2026