Ideal Gas Density Calculator

About this calculator

This calculator finds gas density from the ideal gas law rearranged into ρ = PM / (RT), where P is pressure, M is the gas's molar mass, R is the universal gas constant, and T is absolute temperature. It follows directly from PV = nRT combined with n = mass/M and ρ = mass/V — density rises with pressure and molar mass, and falls as temperature increases.

Chemists and chemical engineers use this to find gas density at non-standard temperature and pressure conditions rather than relying on the STP value, HVAC and combustion engineers use it to correct air density for altitude and temperature, and aviation professionals rely on the same relationship (via air's average molar mass) when density altitude affects aircraft lift and engine performance. Enter pressure, molar mass, and temperature to get density.