Free, instant density altitude and performance tools — built on published FAA and NWS formulas, with the limitations stated plainly.
Every pilot learns about density altitude in ground school — and then meets it for real on a hot afternoon at altitude, when the airplane uses far more runway than the same airplane did in the cool of a sea-level morning. FlightPerformanceCalc exists to make that number instant: no chart, no E6B, no POH lookup, just the conditions from the ATIS and a readout you can trust on a phone at the hangar.
The density altitude calculator computes pressure altitude, ISA deviation, and density altitude from field elevation, altimeter setting (inHg or hPa), temperature (°C or °F), and optional humidity. The all-aircraft performance calculator extends that DA into type-specific estimates — takeoff roll for piston, turboprop, and jet aircraft, and hover ceiling for helicopters.
Everything traces to published, authoritative sources. Pressure altitude and the ISA standard day follow the FAA Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25). The temperature correction uses the precise 118.8 ft per °C factor behind the familiar 120-ft rule of thumb. The optional humidity correction uses the virtual-temperature method published by the National Weather Service — not a made-up multiplier. Where a figure is a rule of thumb, we label it as one.
Density altitude itself is computed with standard-atmosphere math and is accurate for planning at the altitudes where light aircraft operate. Type-specific performance forecasts are generalized models: expect them to land within roughly 15–25% of book figures for typical piston and turboprop aircraft, and treat them as awareness tools. No output of this site replaces your POH/AFM, your weight-and-balance, or an official weather briefing.
The tools are free, work offline after the first visit, and never ask for an account. The site is supported by clearly labeled advertising and affiliate links, disclosed in full in the Disclaimer.
FlightPerformanceCalc is independently built and maintained by a small team of aviation enthusiasts and web developers in the United States. It is not affiliated with the FAA, EASA, any manufacturer, or any military organization. Corrections and suggestions are genuinely welcome — if you find a number that doesn't square with your POH or your training, tell us and we will check it against the source documents.