Air Density Calculator

This page gives the density of air from its temperature, the absolute pressure where it is, and its humidity as either a relative humidity or a dew point. It treats the dry air and the water vapour as separate gases with their own partial pressures and gas constants, adds the two densities, and shows what the same air would weigh if it were dry, which is how it makes clear that humid air is the lighter of the two. You also get the specific volume, the humidity ratio, the density ratio against sea level standard and the density altitude. A second action takes an altitude instead of a barometer reading and uses the standard atmosphere for the pressure.