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Air Density Calculator

Enter the atmospheric pressure, temperature, and relative humidity in the air density calculator to measure the air density of both dry and moist air.

Pa ▾

Air Type

°C ▾

Air Temperature:

Relative Humidity:

Related

The air density calculator quickly computes the density of air in kg/m³ based on temperature and pressure conditions. Additionally, it can determine the dew point, air pressure, and water vapor pressure when the air is compressed.

How to Use the Air Density Calculator?

Follow these steps to calculate air density:

Inputs:

Provide the air pressure value
Select the air temperature
Choose the air type (dry or moist)
Enter the relative humidity
Click the Calculate button to get the results

Outputs: The calculator estimates the following:

Air density
Dew point temperature
Dry air pressure
Water vapor pressure

Air Density Formula:

The density of air can be calculated using this formula:

ρ = [(P_d / (R_d * T)) + (P_v / (R_v * T))]

Where:

P_d = Pressure of dry air
P_v = Water vapor pressure
T = Temperature in Kelvin
R_d = Specific gas constant for dry air [287.058 J/(kg·K)]
R_v = Specific gas constant for water vapor [461.495 J/(kg·K)]

For example, at a temperature of 15 °C and a pressure of 1013.25 hPa, air density is approximately 1.225 kg/m³. Air density, symbolized by ρ, represents the mass of air per unit volume.

Calculating Air Density:

To calculate air density, you need basic atmospheric parameters such as pressure, temperature, and humidity.

Air Pressure:

Air pressure is the force exerted by air molecules on a surface due to gravity. It is typically measured in Pascals using a barometer.

Air Pressure

Common units of pressure include:

Pascals (Pa)
Standard Atmospheres (atm)
Torr
Bar
Pounds per square inch (psi)
Technical Atmospheres (at or kgf/cm²)
Barad (Ba)
Pièze (ps)

Air Temperature:

Temperature can be measured in Kelvin (K), Celsius (°C), or Fahrenheit (°F). Converting units may be necessary when calculating air density.

Air Temperature

Dew Point:

The dew point is the temperature at which water vapor condenses into liquid. You can calculate dew point manually or allow the calculator to compute it automatically based on other inputs.

Air Density in lb/ft³:

The table below shows air density in lb/ft³ at 1 Pascal for different temperatures:

Temperature	Pressure	Air Density (lb/ft³)
15 °C	1 Pa	0.00000075474
20 °C	1 Pa	0.00000074187
22 °C	1 Pa	0.00000073684
25 °C	1 Pa	0.00000072943
40 °C	1 Pa	0.00000069449

Air density can also be expressed in lbm/ft³, sl/ft³ × 10⁻³, lbm/gal (US liquid), and kg/m³. The following table provides density, specific weight, and thermal expansion coefficients at different temperatures:

Temperature (°F)	[lbm/ft³]	[sl/ft³×10⁻³]	[lbm/gal (US liq)]	[kg/m³]	[lbf/ft³]	[N/m³]	Thermal Expansion Coefficient (×10⁻³ °F⁻¹)
-100	0.1104	3.431	0.01476	1.768	0.1104	17.34	2.83
-50	0.0968	3.010	0.01295	1.551	0.0968	15.21	2.48
0	0.0862	2.681	0.01153	1.382	0.0862	13.55	2.20
20	0.0826	2.569	0.01105	1.324	0.0826	12.98	2.10
40	0.0793	2.466	0.01061	1.271	0.0793	12.46	2.02
60	0.0763	2.372	0.01020	1.222	0.0763	11.99	1.94
100	0.0709	2.203	0.00948	1.135	0.0709	11.14	1.80
200	0.0602	1.870	0.00804	0.964	0.0602	9.45	1.53
300	0.0522	1.622	0.00698	0.836	0.0522	8.20	1.30
500	0.0410	1.274	0.00548	0.656	0.0410	6.43	1.05
700	0.0340	1.057	0.00455	0.545	0.0340	5.35	0.88