The instrument panel
Density Altitude Calculator
Enter field elevation, temperature, and altimeter setting — add the dew point for the humidity correction. The gauge shows what altitude the air is behaving like, using the same formulation the National Weather Service publishes.
DENSITY ALTITUDE high DA
Field elevation 5,050 ft — the air behaves like 8,115 ft.
- PRESSURE ALT
- 5,052 ft
- ISA DEVIATION
- —
- RULE-OF-THUMB DA
- —
- AIR DENSITY INDEX
- —
- AIR DENSITY
- —
- WATER · GRAINS/LB
- —
For training and reference · verify with official sources and your POH before flight · no tool on this site renders a go / no-go judgment
Why the airplane thinks it’s higher
Aircraft performance runs on air density. Heat a parcel of air, or drop its pressure, and fewer molecules pass through the prop disc, the wing, and the intake manifold. Density altitude wraps all of that into one number: the altitude in the standard atmosphere where the air would be exactly this dense. Field elevation 5,050 ft on a 95 °F afternoon with a 29.45 setting and a 67 °F dew point reads out above 9,200 ft — the airplane takes off from the field the chart says exists, but climbs like one two ridges higher.
Three things drive the number: elevation (the biggest term), temperature (the one that bites in summer), and pressure (the altimeter setting). Humidity is the quiet fourth — water vapor is lighter than dry air, so a muggy day is a thin day. That is the dew-point correction, applied through virtual temperature exactly as the NWS sheet defines it.
Looking for your home field? The airport lookup carries FAA elevations and NOAA 1991–2020 temperature normals for every public-use field in the 50 states — typical density altitude by month, plus the worst-case summer afternoon.
Frequently asked questions
What is density altitude?
Density altitude is pressure altitude corrected for nonstandard temperature — the altitude the aircraft thinks it is at once heat and pressure are accounted for. On a hot day a runway at 5,000 ft can behave like one at 8,000 ft or more: longer takeoff roll, weaker climb, less thrust. The airplane performs by air density, not by what the sectional says.
How is density altitude calculated here?
This calculator uses the National Weather Service formulation: station pressure from your altimeter setting and elevation, then density altitude from station pressure and virtual temperature. The formulas match the published NWS calculator sheets exactly and are unit-tested against FAA Pilot’s Handbook of Aeronautical Knowledge examples. The familiar training rule of thumb — about 120 ft per °C above ISA — is shown alongside for comparison.
What does the dew point do to density altitude?
Water vapor is lighter than dry air, so humid air is less dense — it adds density altitude. The correction uses virtual temperature: on a muggy summer day it typically adds a few hundred feet compared with the dry-air number. Leave the dew point blank for the dry-air result.
When does density altitude start to matter?
There is no single cutoff, which is why this site never renders a go/no-go. As a reference scale, the readouts here shift to caution amber at 5,000 ft — the range where FAA guidance urges checking POH performance charts closely for normally aspirated aircraft. Your aircraft's numbers come from your POH, not from any calculator.
Can I use this for drag racing?
Yes — the drag racing mode runs the same physics with the labels racers use: density altitude for tuning, air density index in percent against the 60 °F standard day, air density in lb/ft³, and grains of water. It also accepts absolute station pressure straight off a trackside barometer.