Mechanical Efficiency Calculator

Work out mechanical efficiency instantly with clear inputs, formula shown and shareable results.

About Mechanical Efficiency Calculator

Mechanical efficiency is useful output over total input, expressed as a percentage. 7.5 kW delivered from 9.2 kW supplied is 81.5% efficient, with 1.7 kW going into friction, windage and heat. Efficiency can never exceed 100%, and a chain of components multiplies their individual efficiencies together.

Formulas

Efficiency

efficiency = 100 x output / input

Loss

loss = input - output

Worked example

With the default values below, Mechanical Efficiency Calculator returns Mechanical Efficiency of 81.52%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Useful output powerminimum 0 kW: 7.5 kW
Power suppliedminimum 0 kW: 9.2 kW

Results

Mechanical Efficiency: 81.52%
Power Lost: 1.7000 kW
Share Lost: 18.48%
Output-To-Input Ratio: 0.8152

Step by step

1Values used
2Efficiency
3Loss
4Mechanical Efficiency= 81.52
5Power Lost= 1.7000 kW
6Share Lost= 18.48
7Output-To-Input Ratio= 0.8152

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What efficiency is realistic?

Spur gear pairs reach 97-99%, V-belts 93-97%, worm drives only 40-90%, and a whole gearbox is the product of its stages.

Can efficiency exceed 100%?

No. A figure above 100 means the input has been measured wrongly or some energy source has been overlooked.