Free air density calculator using the ideal gas law. Calculate air density for dry or humid air based on temperature, pressure, and humidity.
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Air density is essential for aviation, meteorology, HVAC engineering, and many industrial applications. Our calculator uses the ideal gas law to compute air density from temperature, pressure, and humidity, accounting for both dry and moist air conditions.
Air density (ρ) is the mass per unit volume of Earth's atmosphere. At standard sea level conditions (15°C, 1013.25 hPa), dry air has a density of about 1.225 kg/m³. Density decreases with altitude, increases with pressure, and decreases with temperature.
Ideal Gas Law
ρ = P / (R × T) for dry airAircraft performance depends on air density - lower density reduces lift and engine power.
Air handling systems require accurate density for proper airflow calculations.
Wind turbine power output is directly proportional to air density.
Calculate density altitude for takeoff and landing performance.
Weather models use air density for atmospheric calculations.
Baseball home runs travel farther in lower density air.
Engine performance varies with air density affecting fuel-air mixture.
Counter-intuitively, humid air is lighter! Water molecules (H₂O, 18 g/mol) are lighter than nitrogen (N₂, 28 g/mol) and oxygen (O₂, 32 g/mol), so adding water vapor decreases air density.
Air density decreases about 12% per 1,000 meters (3,300 feet) of altitude. At 5,000m (16,400 ft), density is roughly half that at sea level.
According to the International Standard Atmosphere (ISA), standard sea level density is 1.225 kg/m³ at 15°C and 101,325 Pa. Different standards (IUPAC, NIST) use slightly different conditions.
Aircraft wings generate lift based on air density. Lower density means less lift, requiring longer runways and reducing climb performance. Hot, high-altitude airports are particularly challenging.