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Efficiency Calculator
Find efficiency from useful output and input energy.
How much is not wasted
Efficiency tells you what fraction of the energy you put into a machine comes out as useful work. The rest is lost to heat, friction, and other unavoidable waste.
A motor drawing 1000 joules and delivering 850 of useful work is 85% efficient. Comparing efficiencies reveals which machines and processes waste the least.
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The calculation runs in your browser, so nothing you enter is uploaded.
Frequently Asked Questions
What is efficiency?
The useful energy or work output as a percentage of the energy put in. No real machine reaches 100%.
Why is it never 100%?
Friction, heat, and other losses mean some input energy is always wasted.
What units?
Any, as long as output and input use the same unit.
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