Aircraft power loading explained
Power loading compares aircraft weight with engine horsepower. In piston-aircraft discussions it is usually expressed as pounds per horsepower. It is a simple design and comparison metric: how many pounds of airplane each horsepower is responsible for moving.
Power loading formula
Power loading = aircraft weight ÷ horsepower. A 2,400-pound airplane with a 180-horsepower engine has a power loading of about 13.3 lb/hp. At 2,000 pounds, the same airplane is about 11.1 lb/hp.
What a lower number suggests
All else equal, a lower pounds-per-horsepower number means more installed power is available for each pound of aircraft. That can support stronger acceleration and climb. However, “all else equal” is a major limitation: propeller efficiency, aerodynamic drag, engine power available at altitude, gearing, configuration, and aircraft design all matter.
Why altitude and temperature matter
A normally aspirated piston engine generally produces less power as density decreases with altitude. Hot, high conditions can therefore reduce actual power available even though the engine's rated horsepower has not changed on paper. A simple power-loading calculation based on rated horsepower will not capture that loss.
Weight changes during flight
Fuel burn reduces airplane weight, so the weight-to-power ratio can improve during a flight. Payload changes also matter. When comparing aircraft, make sure the figures use comparable weights and comparable definitions of engine power.
Power loading is not a climb-rate calculator
Two aircraft with the same power loading can have very different climb performance because excess power depends on drag and propulsive efficiency. Use the ratio to understand trends or compare designs, then use POH or AFM data for operational numbers.
Related PilotDesk tools
Wing loading · Density altitude · Climb gradient to FPM