Air Density Calculator
Calculate moist atmospheric air density, dew point, and density altitude from temperature, barometric pressure, elevation, and humidity.
Air Density Calculator (ISA Model)
Did this calculation save you time?
Student ProjectHi! I'm a student developer building Calculat in my spare time. I was tired of searching for basic math tools and having to click through 10 spammy popups, loan ads, and cookie trackers.
I keep this website 100% free, private, and ad-free. If this helped you with your homework, project, or finances today, bookmarking this page or telling a friend helps me keep building more free tools!
What Is a Air Density Calculator?
The Air Density Calculator calculates the density of atmospheric air by applying the ideal gas law for moist air (CIPM / ISA formulations). Because humid air contains water vapor (molecular mass 18 g/mol) that displaces dry air (diatomic nitrogen and oxygen, average molecular mass 29 g/mol), moist air is actually lighter and less dense than dry air.
How to Use This Calculator
- Enter ambient air temperature in °C.
- Enter barometric pressure in hPa/mbar or specify elevation above sea level.
- Enter relative humidity percentage (0% to 100%).
- Review air density in kg/m³ and lbs/ft³, relative percentage of standard sea level, and dew point.
Moist Air Density Equation
\rho = \frac{p_d}{R_d \cdot T} + \frac{p_v}{R_v \cdot T}Where p_d is partial pressure of dry air, p_v is partial pressure of water vapor, R_d is specific gas constant for dry air (287.058 J/(kg*K)), R_v is for water vapor (461.495 J/(kg*K)), and T is absolute temperature in Kelvin.
Worked Example
Scenario: Standard International Standard Atmosphere (ISA) sea level conditions: 15°C, 1013.25 hPa, 0% humidity.
T = 15 + 273.15 = 288.15 K.
p = 101,325 Pa, pv = 0.
Density: 101,325 / (287.058 × 288.15) = 1.2250 kg/m³.
Tips & Key Notes
- High temperature, low pressure, and high humidity all decrease air density, resulting in "high density altitude" that degrades aircraft climb performance and engine horsepower.
- Drag racing and motorsports tuners monitor air density (DA / grains of water) to calibrate air-fuel mixtures for maximum combustion horsepower.
- Baseball fly balls travel significantly farther in thin, low-density air (e.g. Coors Field in Denver at 5,280 ft elevation).
Frequently Asked Questions
Is humid air heavier or lighter than dry air?
Counter-intuitively, humid air is lighter and less dense than dry air. Water vapor molecules (H2O, 18 g/mol) displace heavier nitrogen (N2, 28 g/mol) and oxygen (O2, 32 g/mol) gas molecules.
What is standard sea level air density?
Under the International Standard Atmosphere (ISA) definition at 15°C (59°F) and 1013.25 hPa (29.92 inHg), air density is exactly 1.225 kg/m³ (0.07651 lbs/ft³).
How does elevation affect air density?
Air density drops exponentially with elevation. At 2,000 meters (~6,560 ft), air density is roughly 80% of sea level; at 5,000 meters (~16,400 ft), it is only 60%.
What is density altitude?
Density altitude is pressure altitude corrected for non-standard temperature. It represents the altitude at which the current air density would occur in a standard atmosphere.
Related Calculators
Explore similar toolsDensity Calculator
Calculate density (ρ = m/V), mass, or volume across metric and imperial units with instant multi-unit conversions.
Water Density Calculator
Calculate pure freshwater and ocean seawater density based on temperature (-5°C to 100°C) and salinity (0 to 40 PSU).
Propeller Thrust Calculator
Calculate static aerodynamic thrust, exit airspeed, and absorbed shaft power for airplane, drone, and paramotor propellers.