Density Altitude Calculator

Calculate density altitude from field elevation, altimeter setting, temperature, and dewpoint. Essential for takeoff and landing performance planning.

Inputs

Field Elevation

Sea level to ~14,000 ft for US airports

Altimeter Setting (QNH)

inHg

Typical: 29.82–30.12 inHg

Outside Air Temperature (OAT)

°F

Hot day: 35–40°C, Standard: 15°C at sea level

Tab to move between fields

Results

Density Altitude

8,006 ft

≈ 7 Eiffel Towers

Pressure Altitude5,000 ft

ISA Deviation170.6°F

Relative Humidity29%

Approx. Power Loss24%

Takeoff Distance Increase80%

How to Use This Calculator

Enter your airport's field elevation (from sectional chart or airport directory).
Enter the current altimeter setting from ATIS or METAR.
Enter the outside air temperature (OAT) in Celsius.
Optionally enter the dewpoint for humidity correction.
Use the density altitude result to look up performance in your POH/AFM.

How the result changes across these scenarios

Scenario	Density Altitude
Hot & High (Denver Summer)	9,589 ft
Sea Level Standard	5 ft
Mountain Airport	11,955 ft

What each input means

Field Elevation: Airport elevation above mean sea level (MSL) in feet. Found on sectional charts or airport facility directory.
Altimeter Setting (QNH): Current altimeter setting in inches of mercury. Get from ATIS, AWOS, or METAR.
Outside Air Temperature (OAT): Current outside air temperature in Celsius. Higher temps = higher density altitude = worse performance.
Dewpoint: Current dewpoint temperature in Celsius. Closer to OAT means higher humidity and slightly higher density altitude.

What each result means

Density Altitude: The altitude at which the aircraft 'feels' it is flying — use this for performance chart lookups.
Pressure Altitude: Field elevation corrected for non-standard pressure.
ISA Deviation: How far temperature is from standard. Positive = hotter than standard.
Relative Humidity: Estimated from OAT and dewpoint spread.
Approx. Power Loss: Rough estimate — about 3% per 1,000 ft of density altitude.
Takeoff Distance Increase: Approximate increase in takeoff roll — about 10% per 1,000 ft of density altitude.

How this is calculated

Worked example, using the default values

Pressure Altitude
PA = Field Elevation + (29.92 − Altimeter) × 1000
5,000 + (29.92 − 29.92) × 1000 = 5,000 ft
ISA Standard Temperature
ISA Temp = 15°C − 2°C × (PA ÷ 1000)
15 − 2 × (5,000 ÷ 1000) = 5.0°C
ISA Deviation
Deviation = OAT − ISA Temp
30°C − 5.0°C = +25.0°C
Density Altitude
DA = PA + 120 × ISA Deviation
5,000 + 120 × 25.0 = 8,006 ft