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Instant result
Enter the data and press the button to do the calculation.
Online Calculator
Energy efficiency calculator
Enter the total input and the useful output using the same unit to calculate efficiency and losses.
Use the same quantity and unit for input and output, such as W with W or Wh with Wh.
Information
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Local processing
The values are processed directly in your browser.
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Free
No registration, external API or subscription required.
Frequently asked questions
What is the efficiency formula?
Efficiency = useful output / input × 100.
What units should I use?
Use the same units for input and output.
Can it exceed 100%?
Not in a normal energy balance; the calculator limits useful output to the input value.
Does it also show losses?
Yes, both absolute and percentage.