# Air Density Calculator

Air density is the mass of air per cubic meter. It increases with rising atmospheric pressure, falling temperature and falling humidity. The latter is because a H_{2}O molecule weighs less than a N_{2} or O_{2} molecule. The saturation vapor pressure can be calculated separately. If this is not specified, the calculation is based on the formula for air over water. Please enter at least air pressure and temperature.

The calculation is:

**Gas constant of moist air: R _{f} = R_{t} / [ 1 − φ * E/p * ( 1 − R_{t}/R_{d} ) ]**

With humidity φ between 0 and 1, saturation vapor pressure E in pascals, atmospheric pressure p in pascals, as

the gas constant of dry air R

_{t}= 287.058

and the gas constant of steam R

_{d}= 461.523

The unit of the gas constant is J/(kg*k) = Joule / ( Kilogramm * Kelvin)

**Air density = p / ( R**

_{f}* T)T is the temperature in kelvins = temperature in °C + 273.15

Physics commonly uses SI units. Here is a calculator to convert lengths, temperature, pressure, speed and other units.