Ideal Gas Law Calculator
PV = nRT
atm
L
K
mol
Frequently Asked Questions
What’s the default R value?
We use 0.0821 L·atm/mol·K as the gas constant (R). For different units use our unit converter.
Can I use Celsius temperatures?
Input must be in Kelvin. Our calculator automatically converts from °C (enter formula like “25+273.15”)
What if I’m missing two values?
This calculator requires you to input 3 of the 4 values to calculate the fourth. Input all three known values.
How accurate is this for real gases?
This uses ideal gas law, which works best for gases at low pressure and high temperature. For precision, use real gas equations.
What about SI units?
Available configuration for Pa, m³ or other units is coming in the advanced version.