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Density Altitude Calculator

Enter your field elevation, altimeter setting, and temperature — get density altitude instantly with plain-English warnings about exactly how high DA will affect your takeoff performance.

Enter conditions

Use your current METAR or ATIS. Temperature is the most critical variable.

feet MSL
inHg
degrees Celsius
—
feet MSL
Density Altitude
—
Pressure altitude
ft MSL
—
ISA deviation
°C from standard
—
Std temp at field
ISA reference
—
Engine power %
vs sea level std day

Performance impact — Cessna 172S reference

Approximate figures for a normally aspirated trainer at max gross. Always consult your aircraft's POH performance charts.

ConditionDensity alt (ft)DA vs fieldRunway × factor

Why density altitude matters

Density altitude is pressure altitude corrected for non-standard temperature — it's the altitude your aircraft "thinks" it's at based on air density. High density altitude means thin air: less lift, less thrust, less engine power, and longer takeoff/landing distances.

Pressure Altitude = Field Elevation + (29.92 − Altimeter Setting) × 1,000
Density Altitude ≈ Pressure Altitude + (120 × (OAT°C − ISA Temp°C))
ISA Temp at altitude = 15°C − (2°C × altitude in 1,000 ft)

As a rough rule: every 1,000 ft of density altitude costs about 3% of engine power in a normally aspirated engine, and takeoff ground roll increases roughly 10% per 1,000 ft of DA above sea level. At 8,000 ft DA, you need approximately 80% more runway than at sea level.

Density altitude accidents are disproportionately fatal. High-DA departures — especially from short or uphill strips on hot summer days — are a leading cause of fatal GA accidents. The FAA calls DA the "silent killer" because the conditions feel normal until performance falls dangerously short. When in doubt: reduce weight, depart early in the morning when temperatures are lowest, or wait for cooler weather.

Turbocharged and FADEC-equipped engines maintain power better at altitude. Check your specific aircraft's performance charts — a turbo Cessna 182 behaves very differently from a naturally aspirated 172 at the same density altitude.