Ideal Gas Law Calculator
Solve PV = nRT for whichever term you are missing.
How it works
PV = nRT, with R = 8.314462618 J/(mol·K) in SI units.
The law describes a gas whose molecules have no volume and no attraction to each other. Real gases follow it closely at low pressure and high temperature, and depart from it as they approach condensation — which is precisely when you most want an accurate answer.
Temperature must be absolute. Using Celsius is the single most common error here, and near room temperature it is wrong by a factor of about twelve.