Motor Efficiency
Use the Motor Efficiency. Enter Output power (kW) and Input power (kW) for a clear result, formula explanation, and practical planning checks.
Motor Efficiency measurements
Enter your values, then calculate.
Result
How to calculate motor efficiency
This calculator finds motor efficiency by dividing output power by input power — the standard metric for how much of the electrical energy supplied to a motor converts to useful mechanical output.
How the calculation works
Efficiency = (Output power ÷ Input power) × 100.
Example
A motor delivering 7.5 kW output from 8.5 kW input: Efficiency = (7.5 ÷ 8.5) × 100 ≈ 88%.
Frequently asked questions
How is Result calculated?
Result = ([Output power] ÷ [Input power]) × 100.
Is the Motor Efficiency free to use?
Yes — every calculator on Simple Calculator Tools is free, runs in your browser, and does not require an account.
Motor Efficiency
Efficiency = (Output power ÷ Input power) × 100.
Let's understand your motor efficiency result.
Calculate a result above and this guide will help you interpret it using this calculator's own formula and explanation.
Pro Tips for Motor Efficiency
- Motor efficiency typically varies with load — a motor running well below its rated load often operates less efficiently than at its optimal load point.
- Compare efficiency at similar load levels when evaluating motor replacement options, since efficiency ratings are usually specified at full rated load.
Common Motor Efficiency Mistakes to Avoid
- Comparing motor efficiency ratings measured at different load levels as if they were directly comparable, when efficiency curves vary with load.
When to Use This Calculator
This calculator finds motor efficiency by dividing output power by input power — the standard metric for how much of the electrical energy supplied to a motor converts to useful mechanical output.