Air Density Calculator
Estimate moist-air density from temperature, relative humidity and station pressure.
What would you like to do next?
Combine dry-air and water-vapor contributions
Enter temperature, relative humidity and station pressure in hectopascals or inches of mercury. The calculator estimates water-vapor partial pressure, subtracts it from total pressure for the dry-air share and applies separate gas constants before adding the two density contributions. It also displays specific volume, the reciprocal cubic meters occupied per kilogram.
Pressure type and standard matter
Station pressure is the actual local pressure and should not be confused with a sea-level altimeter setting. Humidity sensor error, extreme conditions and departures from ideal-gas behavior affect the estimate. Aerodynamic, metrology and industrial calculations can require a particular atmosphere standard, compressibility treatment and instrument correction.
Explore the next step: Wind Turbine Power interactive lab. See how air density enters an ideal wind-power model alongside rotor diameter and wind speed.
Frequently asked questions
Which pressure should I enter?
Use local station pressure rather than a pressure reduced to sea level.
Why does humidity affect density?
Water-vapor molecules replace some heavier dry-air molecules at the same total pressure.
What is specific volume?
It is the reciprocal of density, shown here as cubic meters per kilogram.