What this calculator does
This tool calculates the density of any gas that behaves approximately ideally, based on its pressure, temperature, and molar mass, using the ideal gas law.
The formula
Starting from PV = nRT and density ρ = m/V = nM/V, the density is ρ = PM / (RT), where P is absolute pressure, M is the gas’s molar mass, R is the universal gas constant (8.314462618 J/(mol·K)), and T is absolute temperature in Kelvin.
This formula assumes ideal gas behavior, which is a good approximation for most gases at normal temperatures and moderate pressures, but becomes less accurate at very high pressure or very low temperature.
Last reviewed August 2026