Density Altitude Calculator
Calculate density altitude from field elevation, altimeter setting, and outside air temperature.
Critical for takeoff and climb performance planning.
What is density altitude?
Density altitude is the altitude at which the air density equals the actual air density at your location. It is the “performance altitude” of the aircraft — what the aircraft experiences regardless of where it physically is.
A sea-level airport on a hot, low-pressure day can have a density altitude of 3,000–5,000 ft, meaning the aircraft performs as if it were at a 3,000–5,000 ft elevation airport.
Why it matters
At high density altitude:
- Engines produce less power (less oxygen per combustion cycle)
- Propellers produce less thrust (less dense air per rotation)
- Wings produce less lift (less dense air over the aerofoil)
- Takeoff roll is significantly longer — sometimes dangerously so
- Rate of climb is reduced — sometimes to near zero when fully loaded
The FAA formula for density altitude:
Pressure Altitude = Field Elevation + (29.92 − Altimeter Setting) × 1,000 ft ISA Temp = 15 − (Pressure Altitude ÷ 1,000 × 2) °C Density Altitude = Pressure Altitude + 120 × (OAT − ISA Temp)
High-and-hot operations
“High and hot” — high elevation combined with high temperature — is the most dangerous combination for density altitude. In mountainous regions during summer afternoons, density altitudes routinely exceed 8,000–10,000 ft even at airports below 5,000 ft MSL. Many accidents occur because pilots underestimate density altitude effects. Always use your aircraft’s POH performance charts for actual takeoff and climb data.