✈️ Density Altitude Calculator
Calculate density altitude from field elevation, altimeter setting, and outside air temperature. Density altitude is the pressure altitude corrected for non-standard temperature — it tells you how the aircraft feels the air density. Includes pressure altitude, ISA temperature, and optional humidity correction.
What Is Density Altitude?
Density altitude is the pressure altitude corrected for non-standard temperature. It represents the altitude at which the aircraft feels it is flying, based on the actual air density. On a hot day, the air is less dense, so the aircraft performs as if it were at a higher altitude — this is the density altitude.
Density altitude is critical for flight safety because it directly affects:
- Takeoff distance — higher DA means longer takeoff roll.
- Climb rate — higher DA means slower climb.
- Engine power — naturally aspirated engines produce less power at high DA.
- Lift generation — wings generate less lift in thinner air.
How to Calculate Density Altitude
The calculation involves three steps:
Step 1 — Pressure Altitude: PA = (29.92 − Altimeter Setting) × 1000 + Field Elevation
Step 2 — ISA Temperature: ISA Temp = 15 − 2 × (PA / 1000)
Step 3 — Density Altitude: DA = PA + 120 × (OAT − ISA Temp)
For example, at a field elevation of 2,000 ft with an altimeter setting of 29.92 inHg and an OAT of 30 °C:
PA = (29.92 − 29.92) × 1000 + 2000 = 2,000 ft
ISA Temp = 15 − 2 × (2000/1000) = 11 °C
DA = 2000 + 120 × (30 − 11) = 2000 + 2280 = 4,280 ft
This means the aircraft performs as if it were at 4,280 ft instead of 2,000 ft — a significant reduction in performance.
Humidity Correction
Humidity also affects air density — moist air is less dense than dry air. A rule of thumb is that the humidity correction in feet is approximately 20 × dew point temperature (°C)[reference:1]. For example, a dew point of 15 °C adds roughly 300 ft to the density altitude. Most aircraft performance charts assume 0% humidity, so this correction can be important on humid days.
Why Use This Calculator?
- Instant results: Get pressure altitude, ISA temperature, and density altitude in seconds.
- Step-by-step breakdown: See exactly how each value is calculated.
- Humidity correction: Optional dew point input for more accurate results.
- Performance impact indicator: See how density altitude affects aircraft performance.
- Free & private: No registration, no data storage — all calculations are done in your browser.
❓ Density Altitude Calculator FAQ
What is the formula for density altitude?
The formula is DA = PA + 120 × (OAT − ISA Temp), where PA is pressure altitude, OAT is outside air temperature, and ISA Temp is the standard temperature at that pressure altitude.
What is the difference between pressure altitude and density altitude?
Pressure altitude is the altitude above the standard datum plane (based only on pressure). Density altitude is pressure altitude corrected for non-standard temperature — it represents the altitude the aircraft actually "feels"[reference:2].
How do I calculate pressure altitude?
Pressure Altitude = (29.92 − Altimeter Setting) × 1000 + Field Elevation. Alternatively, set the altimeter to 29.92 and read the altitude directly[reference:3].
What is ISA temperature?
ISA (International Standard Atmosphere) temperature at a given pressure altitude is calculated as 15 °C − 2 °C per 1,000 ft. At sea level, ISA is 15 °C; at 5,000 ft, it's 5 °C; at 10,000 ft, it's −5 °C.
Why does density altitude matter for pilots?
Density altitude affects takeoff distance, climb rate, engine power, and lift generation. High density altitude (hot day, high elevation) significantly degrades aircraft performance and is a major factor in many aviation accidents[reference:4].
How does humidity affect density altitude?
Humid air is less dense than dry air, so it increases density altitude. A rule of thumb is to add approximately 20 ft per °C of dew point. For example, a dew point of 20 °C adds about 400 ft to the density altitude[reference:5].
What is a high density altitude?
There's no universal threshold, but many flight schools and aviation authorities consider density altitude above 5,000 ft to be a concern, and above 8,000 ft to be potentially dangerous for normally aspirated aircraft.
How accurate is this calculator?
This calculator uses standard aviation formulas for pressure altitude, ISA temperature, and density altitude. The humidity correction is a rule of thumb. For critical flight decisions, always use your aircraft's approved performance charts and official weather data.
Is this calculator free?
Yes, this calculator is completely free to use. No registration or personal data storage is required.
What is the standard temperature lapse rate?
The standard lapse rate is 2 °C per 1,000 feet (or 6.5 °C per 1,000 meters) in the troposphere. This is used to calculate ISA temperature at any pressure altitude.