E6BPilot Computer
Free calculator

Density altitude calculator

Density altitude from field elevation, the altimeter setting and the outside air temperature, with the working shown. Results update as you type.

Example values — change any of them
inHg

The altimeter setting from the ATIS or METAR.

ft

Field elevation from the airport chart.

°C

Outside air temperature at the field.

Units
Density Altitude
8,124 ft
Pressure Altitude
5,100 ft

Density altitude 8,124 ft, at a pressure altitude of 5,100 ft.

PA = elev + (29.92 − altimeter) × 1000ISA_T = 15 − 2 × (PA/1000)DA = PA + 120 × (OAT − ISA_T)E6B rule of thumb: 120 ft per °C of ISA deviation. Computed in ft · °C · inHg.

Worked example — with your numbers

  1. PA = 5,000 + (29.92 − 29.82) × 1000 = 5,100 ft
  2. ISA_T = 15 − 2 × (5,100/1000) = 4.8 °C
  3. DA = 5,100 + 120 × (30 − 4.8) = 8,124 ft

What density altitude tells you

Density altitude is the altitude in the standard atmosphere where the air would be as dense as the air around you. The aircraft and engine perform as if they were at that altitude, so on a hot day at a high field it can sit thousands of feet above the field elevation, with longer takeoff runs and weaker climbs to match.

The calculator works out pressure altitude from the altimeter setting first, then compares the outside air temperature with the standard (ISA) temperature for that pressure altitude: 15 °C at sea level, falling about 2 °C for every 1,000 ft.

A rule of thumb, not a performance chart

Adding 120 ft for every degree Celsius above standard is the E6B approximation. It ignores humidity, which raises density altitude a little further. For takeoff and landing distances, use the performance charts in your aircraft’s documents.

Pressure altitudeCrosswindCloud baseUnit converterWeight and balance

Solve it on your iPhone. The same density altitude math, a keypad built for the cockpit, and METAR paste that fills in the altimeter setting and temperature. The free calculators stay free.

App Store · coming soon
Safety

For training and supplemental situational awareness only. Not for use as the sole basis for flight planning, performance, or operational decisions. It is not an approved flight planning tool, electronic flight bag (EFB), or primary source of aeronautical information. Always use current aircraft documents, an official briefing, and pilot judgment.