η
Efficiency Calculator
How much of the energy or power going in comes out as useful work, and how much is wasted.
Result…
How it's calculated
η = useful output ÷ input × 100%
Efficiency is the share of energy or power going in that comes out as something useful; the rest is lost, mostly as heat. Use the same unit for input and output. Electric motors often reach 85–95%, car petrol engines typically 20–35%, and nothing reaches 100%.
Your numbers, step by step
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