What is the density altitude formula?

A common pilot approximation is Density Altitude = Pressure Altitude + 120 * (Outside Air Temperature - ISA Temperature), using temperature in degrees Celsius.

How do you calculate pressure altitude?

Pressure altitude is calculated as field elevation + (29.92 - altimeter setting) * 1000 when elevation is in feet and altimeter setting is in inches of mercury.

Does humidity increase density altitude?

Yes. Moist air is less dense than dry air, so high humidity can increase density altitude, especially on hot days.

Density Altitude Calculator

Calculate density altitude from field elevation, altimeter setting, outside air temperature, dew point, or relative humidity.

Examples:

Airport Pressure Data

Enter field elevation and the current altimeter setting from METAR, ATIS, AWOS, ASOS, or tower.

Field Elevation 5,000 ft

Altimeter Setting 29.92 inHg

How to Use the Density Altitude Calculator

This aviation density altitude calculator is designed for quick preflight planning. Enter the airport elevation, pressure setting, outside air temperature, and optional humidity data to estimate how the aircraft will perform in the current air mass.

Step 1: Enter field elevation in feet or meters.

Step 2: Provide the altimeter setting or QNH from METAR, ATIS, AWOS, or ASOS.

FAA/NWS METAR Key

Step 3: Input outside air temperature and dew point or relative humidity.

Step 4: Review density altitude, pressure altitude, ISA deviation, and performance guidance.

How it Works

The calculator first converts field elevation and altimeter setting into pressure altitude. It then compares outside air temperature against ISA temperature and refines the result with moist-air density when humidity data is available.

Pressure Altitude: The starting altitude after correcting field elevation for pressure.
Density Altitude: Pressure altitude corrected for nonstandard temperature, with humidity estimated from moist-air density.

FAA Pilot's Handbook aircraft performance chapter

Density Altitude and Aircraft Performance Explained

Understand why hot, high, and humid conditions can reduce takeoff, climb, engine, and propeller performance.

Pressure Altitude

Pressure altitude is field elevation adjusted to the standard pressure plane. Pilots commonly estimate it from airport elevation and the altimeter setting. Low pressure raises pressure altitude and can reduce aircraft performance before temperature is even considered.

Temperature and Humidity

Warm air is less dense than cold air, so a hot day can make the aircraft perform as if it were at a much higher altitude. Moist air is also less dense than dry air, which is why dew point or relative humidity can refine the final density-altitude estimate.

FAA definition of density altitude

Density Altitude Formula

The quick pilot formula is ideal for mental math and E6B-style planning. The calculator also computes a humidity-aware value from moist-air density.

Pressure Altitude Formula

PA = elevation + (29.92 - altimeter) * 1000

Density Altitude Approximation

DA ~= PA + 120 * (OAT - ISA)

Use temperature in Celsius for the quick approximation. Humidity-aware density altitude compares moist-air density against the ISA density model.

FAA density altitude chart

Find Pressure Altitude

Correct field elevation using the altimeter setting or QNH. Lower-than-standard pressure increases pressure altitude.

Compare OAT to ISA

Find ISA temperature at pressure altitude, then calculate how many Celsius degrees the day is above or below standard.

Estimate Density Altitude

Add 120 feet per Celsius degree above ISA, then refine with dew point or relative humidity if available.

Density Altitude Calculation Example

Suppose an airport elevation is 5,000 ft, the altimeter setting is 29.92 inHg, and outside air temperature is 30C:

Pressure Altitude5,000 ft

ISA Deviation30C - 5C = +25C

Density Altitude5,000 + 120 * 25 = 8,000 ft

METAR Inputs for Density Altitude

Use METAR, ATIS, AWOS, or ASOS data carefully. This calculator uses altimeter setting or QNH, not raw station pressure. Aviation Weather Center METAR/TAF data

Weather Data	Calculator Input	Example
Airport elevation	Field elevation	5,000 ft
A2992 or Q1013	Altimeter / QNH	29.92 inHg
Temperature group	Outside air temperature	35C
Dew point group	Dew point	12C
Pilot charts	POH/AFM performance check	Required

How Pilots Interpret Results

High density altitude can make a normally safe runway marginal. The same aircraft weight, runway, and wind can produce very different takeoff and climb performance after temperature or pressure changes.

After calculating density altitude, compare the result with official aircraft POH/AFM takeoff, climb, landing, and obstacle-clearance data before making operational decisions. Review FAA takeoff performance guidance .

Critical Safety Notice

This calculator is for educational and preflight planning reference only. Use official weather, airport data, aircraft documentation, flight training, and pilot judgment for actual flight operations.

High Density Altitude Checklist

The density-altitude number is a warning signal, not a performance chart. Treat it as the starting point for a conservative aircraft-specific takeoff and climb analysis.

Aircraft Weight

Reduce weight when performance charts show limited climb or runway margin.

Runway Surface

Grass, soft fields, uphill slope, or contaminated surfaces increase ground roll.

Wind and Obstacles

Headwind can help, but tailwind and terrain can quickly erase performance margin.

Mixture and Leaning

Normally aspirated engines may need proper leaning before takeoff at high elevations.

Density Altitude FAQ

Common pilot questions about pressure altitude, temperature, humidity, METAR data, and aircraft performance.

What inputs do I need to calculate density altitude?

Use field elevation, altimeter setting or QNH, outside air temperature, and optionally dew point or relative humidity for humidity-aware density altitude.

What is density altitude?

Density altitude is pressure altitude corrected for nonstandard temperature. This calculator also computes a humidity-aware result from moist-air density.

Is density altitude the same as pressure altitude?

No. Pressure altitude adjusts elevation for pressure. Density altitude adjusts pressure altitude for nonstandard temperature, and this calculator can also refine the result for humidity.

How do I calculate pressure altitude from altimeter setting?

Use PA = field elevation + (29.92 - altimeter setting) * 1000. If the altimeter setting is below 29.92, pressure altitude is higher than field elevation.

Why does hot weather increase density altitude?

Warm air is less dense. Less dense air reduces wing lift, propeller thrust, and engine power, which increases takeoff distance and decreases climb rate.

Does humidity matter for density altitude?

Yes. Moist air is less dense than dry air, so high humidity can raise density altitude. Temperature and pressure usually dominate, but humidity is meaningful on hot moist days.

Can I calculate density altitude from a METAR?

Yes. Use airport elevation, the METAR altimeter setting or QNH, the temperature, and the dew point. For example, 35/12 means OAT 35C and dew point 12C.

Can I use this instead of my POH or AFM?

No. Use this calculator for awareness and preflight planning, then verify takeoff, climb, landing, and obstacle-clearance performance with official aircraft data.