Work out air density at altitude instantly with clear inputs, formula shown and shareable results.
Air density follows from the barometric pressure at altitude divided by the gas constant times absolute temperature. At 1500 m and 10 C the pressure is 845 hPa and density 1.04 kg/m3, about 85% of sea level. Aircraft performance, engine power and aerodynamic drag all scale with this figure, which is why density altitude is what pilots actually use.
Barometric pressure
P = 101325 (1 - 0.0065h / 288.15)^5.25588
Air density
rho = P / (287.058 x T in kelvin)
Because warm air is less dense, cutting both lift and engine thrust. A hot day at altitude can add hundreds of metres to take-off distance.
The altitude at which standard atmosphere would have the density you actually have - the figure that governs performance.