Mechanical Efficiency Calculator

Enter useful output and input energy to compute mechanical efficiency.

How to use

  1. Enter your values in the fields above.
  2. Press Calculate to see your result instantly.
  3. Use the Share button to copy a link to your result.

About this calculator

Mechanical efficiency is the percentage of energy put into a machine that comes out as useful work, calculated as η = (useful output energy ÷ input energy) × 100%. This calculator also reports the energy lost — the input minus the output — which represents waste typically dissipated as heat, friction, vibration, or noise, since no real machine is ever 100% efficient.

Mechanical engineers, HVAC technicians, and machine designers use this ratio to rate engines, gearboxes, pumps, pulley systems, and electric motors, and to compare competing designs or diagnose when a machine is underperforming its rated output. In everyday contexts it also explains why, for example, a bicycle drivetrain (often 95%+ efficient) wastes far less energy than an internal combustion engine (commonly 20-35% efficient).

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