Air Density Calculator (Temperature, Pressure, Humidity)
Enter the temperature, pressure and humidity.
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Air Density Calculator (Temperature, Pressure, Humidity) by TheCalcTools
How the Air Density Calculator (Temperature, Pressure, Humidity) works
Air density is the sum of the dry air and water vapour partial densities from the ideal gas law: ρ = p_d ÷ (R_d T) + p_v ÷ (R_v T), with R_d = 287.058 and R_v = 461.495 J/(kg·K). The vapour pressure uses the Tetens formula.
Humid air is slightly lighter than dry air because water molecules are lighter than nitrogen and oxygen. Density affects aircraft lift, engine power and the flight of a ball.
The formula
Worked example
Using the default values shown in the calculator:
| Temperature (°C) | 25 |
|---|---|
| Air pressure (hPa) | 1013.25 |
| Relative humidity | 50 % |
- At 25 °C, 1013.25 hPa and 50% humidity the air density is 1.1769 kg/m³.
Result:
| Air density (kg/m³) | 1.1769 |
|---|---|
| Dry air at the same temperature and pressure (kg/m³) | 1.1839 |
| Compared with the standard 1.225 kg/m³ | 96.1% |
| Water vapour pressure (hPa) | 15.84 |
Frequently asked questions
What is standard air density?
1.225 kg/m³ at sea level, 15 °C and 1013.25 hPa in the International Standard Atmosphere.
Sources and further reading
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