Air Density Calculator
Calculate air density from temperature, pressure, and altitude.
Used for wind turbine power corrections, aviation, and aerodynamics.
Air density determines how much mass of air passes through a wind turbine rotor or aircraft wing. Lower air density means less energy available per cubic metre — this matters at altitude and in hot weather.
Ideal gas formula: rho = P / (R × T)
Where:
- rho = density (kg/m³)
- P = atmospheric pressure (Pa)
- R = specific gas constant for dry air = 287.058 J/(kg·K)
- T = temperature in Kelvin (°C + 273.15)
Standard atmosphere (ISA) values:
- Sea level (0 m): 1.225 kg/m³ at 15°C and 101,325 Pa
- 1,000 m altitude: ~1.112 kg/m³
- 2,000 m altitude: ~1.007 kg/m³
- 5,000 m altitude: ~0.736 kg/m³
Effect on wind turbine power: Power ∝ air density, so at 2,000 m altitude: Power output = sea-level power × (1.007 / 1.225) = 82% of sea-level value
A turbine rated at 5 kW at sea level produces only ~4.1 kW at 2,000 m altitude.
Worked example: Temperature 30°C (303 K), pressure 100,000 Pa (slightly low, 800 m altitude): rho = 100,000 / (287.058 × 303) = 100,000 / 86,979 = 1.150 kg/m³ Power correction factor = 1.150 / 1.225 = 0.939 (6.1% less than standard)