Altitude calculations
Choose a focused calculator for pressure altitude or density altitude.
Pressure altitude
Find the standard-pressure altitude from airfield elevation and QNH. Explore the QNH, QNE and QFE reference diagram.
Open calculator →02 · AIR DENSITYDensity altitude
Add outside air temperature to estimate the altitude your aircraft experiences for performance planning.
Open calculator →Two altitudes, two questions.
Pressure altitude
Pressure altitude is what a correctly functioning altimeter indicates when set to standard pressure, 1013.25 hPa (29.92 inHg). We estimate airfield pressure from QNH and airfield elevation using the standard atmosphere, then find the corresponding pressure altitude.
Density altitude
Density altitude describes air density as an equivalent altitude in the standard atmosphere. The density altitude calculator uses the common planning approximation: pressure altitude plus 120 ft for each °C that the outside temperature is above the standard temperature at that pressure altitude.
Density altitude ≈ pressure altitude + 120 × (OAT − ISA temperature) ftWhat each setting means.
QNH makes the altimeter read the airfield elevation above mean sea level while on the airfield.
QNE means the standard setting, 1013.25 hPa / 29.92 inHg. The indication is pressure altitude, used as the common flight-level reference where applicable.
QFE is local pressure at the airfield reference datum; when set, the altimeter reads approximately zero at that datum. Its indicated height is relative to the airfield, not mean sea level.
Definitions and method: FAA Pilot’s Handbook of Aeronautical Knowledge · FAA aeronautical contractions · FAA density altitude approximation
QFE is estimated from QNH using a standard-atmosphere altimeter model. Density altitude is approximate and does not account for humidity. Verify the current altimeter setting and use approved aircraft performance charts and local procedures before flight.