Atmospheric Properties Calculator

The amount of water that air can hold is affected by its temperature.
The amount of water it does hold is described by the Dew Point, two parcels of air with the same saturation vapour pressure have the same Dew Point.
When the temperature and dew point match the air is saturated, this is 100% Relative Humidity.
It can be easily proven using these figures that moist air is less dense than dry air (humidity affects performance) even though this seems counter intuitive, it must be remembered that water vapour is water in gaseous form not liquid and that is the density we are dealing with.
METAR
Sea Level Pressure  mb
Temp °C
Dew Point °C
Indicated Altitude [QNH Set] ft

Sea Level Air Properties

Saturation Vapour Pressure 0.0000 mb
Dry Air Pressure 1,013.25 mb 34,314.02 inHG
Density 1.2250 Kg m-3
Relative Humidity0.00%
Density Altitude
Including Humidity
-0.33ft [Calculated to include humidity effects, not the usual DA calculation used in aviation]

Air Properties at Altitude

Density Altitude 0ft [PA +/- 120ft per Degree ISA Temp Deviation]