Calculate the thermodynamic properties of air.

m3/kgdry air
J/kgdry air

Psychrometric Chart


Reference Pressure: Default value of 101325 Pa represents the standard atmospheric pressure (1 atm).

Dry Bulb Temperature: Temperature of air measured by a thermometer freely exposed to the air. This is the temperature that is indicated by an ordinary thermometer.

Relative Humidity: Ratio of partial pressure of moisture to partial pressure of moisture at saturation.

Absolute Humidity: Moisture content of a gas by mass.

Wet Bulb Temperature: Temperature read by a thermometer covered in by a wick wetted with water which moved through air unsaturated with water vapor. At 100 % relative humidity, the wet-bulb temperature is equal to the air temperature (dry-bulb temperature). At lower humidity the wet-bulb temperature is lower than dry-bulb temperature.

Dew Point Temperature: Temperature at which moisture begins to condense when mixture is cooled.

Vapor Pressure: Pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature in a closed system.

Specific Volume: Ratio of a substance volume to its mass. It is the reciprocal of density.

Specific Enthalpy: Ratio of a system enthalpy to its mass.


D. Meyer and D. Thevenard (2019). PsychroLib: a library of psychrometric functions to calculate thermodynamic properties of air. Journal of Open Source Software, 4(33), 1137

American Society of Heating, Refrigerating and Air-Conditioning Engineers (2017). ASHRAE handbook fundamentals 2017: SI edition. Atlanta, GA: ASHRAE.

D.W. Green and R.H. Perry (2008). Perry's Chemical Engineers' Handbook, McGraw-Hill.