Density Altitude Calculator

Worked Example

An airport at 5,000 ft MSL with an altimeter of 29.72 inHg and OAT of 35°C:

• PA = 5,000 + (29.92 − 29.72) × 1,000 = 5,200 ft
• ISA at 5,200 ft = 15 − (5.2 × 1.98) = 4.7°C
• ISA Deviation = 35 − 4.7 = +30.3°C
• DA ≈ 5,200 + (120 × 30.3) = 8,836 ft

Why This Matters to Pilots

Density altitude is the single most important performance factor. On a hot day at a high-elevation airport, density altitude can exceed the field elevation by thousands of feet, dramatically reducing takeoff performance, climb rate, and engine power.

The famous "high, hot, and humid" conditions at airports like Denver (5,431 ft) or Leadville (9,934 ft) can push density altitude well above 10,000 ft, meaning the aircraft performs as if it were at that altitude.

Always check density altitude before every flight and compare performance data to your aircraft's POH charts.

Limitations & Assumptions

• Uses the standard lapse rate (1.98°C/1000 ft) which is an average, not actual conditions.
• The 120-factor approximation is less accurate at extreme altitudes or temperatures.
• Humidity correction (when dewpoint is entered) uses the Bolton 1980 vapor pressure formula.
• Does not account for non-standard lapse rates or temperature inversions.