Mechanical Efficiency Calculator

How it is calculated

The tool divides useful output energy by input energy: η = output ÷ input × 100%, and the lost energy is loss = input − output. Both values must be in the same energy unit, and the loss is labelled in joules, so enter joules (or convert first). Input must be above zero, output cannot be negative, and output larger than input is refused because a machine cannot return more energy than it receives. An output equal to the input gives 100% and zero loss. The same ratio works for power if both values are power in the same unit, but the loss label would still say J. The tool does not say where the loss goes (friction, heat, noise).

Common mistakes

• Swapping input and output; a value above 100% is impossible and the tool refuses it.
• Mixing units, for example input in kWh and output in joules, so the ratio is thousands of times off.
• Counting the energy of the load only partly: for a lift, useful output is the potential energy gained (m × g × h), not the electric energy consumed.
• Using the rated output of the machine instead of measured output; a catalogue figure gives the nameplate efficiency, not the real one under your load.
• Multiplying efficiencies the wrong way for systems in series; for a motor then a gearbox, multiply the two efficiencies, do not add them.