Efficiency Calculator

About this calculator

This calculator finds efficiency as a percentage: useful output divided by total input, multiplied by 100. It's the same ratio engineers use to rate motors, engines, and machines, and the same logic anyone can apply to any process where some input is "lost" along the way.

Mechanical and electrical engineers use it to rate motors, pumps, and power supplies; students use it for physics and thermodynamics homework; and operations staff use it to measure how much of a process's input actually turns into useful work. Just enter the useful output and total input in matching units.