Air Density Calculator - Calculator Academy

Reviewed By: Patrick Myers (BSME)

Enter the dry-air partial pressure (p_d), water vapor partial pressure (p_v), and air temperature into the air density calculator. If you only know total air pressure p, first compute p_d = p − p_v. The calculator will display the current air density at those conditions.

Air Density Formula

The following formula is used to calculate air density for moist air using the partial pressures of dry air and water vapor (total pressure p = p_d + p_v).

ρ = (pd / (Rd * T)) + (pv / (Rv * T))

where:

pd is the partial pressure of dry air in Pa,
pv is the partial pressure of water vapor in Pa,
T is the air temperature in Kelvins,
Rd is the specific gas constant for dry air equal to 287.058 J/(kg·K), and
Rv is the specific gas constant for water vapor equal to 461.495 J/(kg·K).

Air Density Definition

Air density is the mass per unit volume of air under a given temperature and pressure (and it can also vary with humidity).

How to calculate air density?

1.First, determine the pressure of dry air
- This is the dry-air partial pressure p_d. If you know total pressure p and water vapor pressure p_v, then p_d = p − p_v.
2.Next, determine the water vapor pressure
- This is dependent on the relative humidity.
3.Measure the air temperature
- Measure the air temperature and convert it to Kelvin.
4.Calculate the air density
- Calculate the air density using the formula above.

FAQ

What is air density?

Air density is the total mass of air within a given volume.

How can air density change?

Air density can change with temperature and pressure. Increasing pressure increases density (at a given temperature). Increasing temperature decreases density (at a given pressure).