All Tools
Air Density & Density Altitude
Heat, humidity and altitude all rob an engine of oxygen. Know the air you’re actually breathing: density in kg/m³, density altitude, and roughly what the day costs your lap times.
°C
%
hPa
Air density
1.136 kg/m³
Density ratio vs ISA
92.8%
Density altitude
652 m
2,138 ft
NA power vs sea level
-7.2%
Station pressure used: 1,008 hPa (vapour pressure 33.3 hPa). Rules of thumb: NA engines lose ~3% per 1000 ft of density altitude; 10 °C of heat ≈ 1.9% of density ≈ similar power. EFI compensates fuelling automatically — what it can’t compensate is the missing oxygen. A turbo can chase density with more boost, but the compressor runs hotter and further up its map.
Good to know
- Station pressure, not sea-level pressure: if you enter “from altitude”, standard atmosphere pressure is assumed — a low-pressure day shifts the numbers.
- Formula set: Magnus vapour pressure + dry/wet air densities; density altitude uses the NWS formula, converted to metres.
- Rules of thumb: naturally aspirated engines lose about 3% power per 1,000 ft of density altitude; 10 °C of heat is worth ~1.9% of density.
- Turbos can chase density with more boost, but they pay in compressor speed, heat and further up the map — compare lb/min, not just boost numbers.