Science & engineering
Energy efficiency calculator
Compare useful energy output with total energy input.
A clear answer. Here’s how.
Efficiency = useful energy output ÷ total energy input × 100. Useful output cannot exceed input in this energy-balance definition. Also shows the unaccounted energy difference. Heat-pump coefficient of performance is a different measure.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Total energy input (joules)
- 1000
- Useful energy output (joules)
- 800
Example result
- Efficiency
- 80%
- Energy difference (J)
- 200