Motor Efficiency Calculator
Electric motor efficiency from input and output power.
Enter your values
Enter the supply voltage in V.
Enter the current draw in A.
Enter the power factor you are working with.
Enter the rated output in hp.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Input power
- 1564 W
- Output power
- 1118.6 W
- Motor efficiency
- 71.5%
- Power lost as heat
- 445.4 W
Quick answer
Efficiency = output power / input power x 100%.
eff = Pout/Pin x 100
At a glance
| What it does | Electric motor efficiency from input and output power. |
|---|---|
| Category | Engineering |
| Inputs needed | Supply voltage, Current draw, Power factor, Rated output |
| Main output | Input power |
| Formula | eff = Pout/Pin x 100 |
| Cost | Free — no sign-up, no download |
How to use the Motor Efficiency Calculator
- 1Enter the motor's electrical supply voltage, current and power factor.
- 2Enter the rated mechanical output in horsepower.
- 3Read the calculated efficiency and heat losses.
Inputs explained
- Supply voltage(V)
- Enter the supply voltage in V.
- Current draw(A)
- Enter the current draw in A.
- Power factor
- Enter the power factor you are working with.
- Rated output(hp)
- Enter the rated output in hp.
Worked example
Using the values the calculator loads with:
Inputs
- Supply voltage230 V
- Current draw8 A
- Power factor0.85
- Rated output1.5 hp
Results
- Input power1564 W
- Output power1118.6 W
- Motor efficiency71.5%
- Power lost as heat445.4 W
Frequently asked questions
What is a typical motor efficiency?
Standard motors run 80-90% efficient; premium efficiency motors can exceed 95%.
Why does power factor matter here?
Input real power depends on power factor; ignoring it overstates the electrical input.
What do I need to enter into the Motor Efficiency Calculator?
Just 4 values: supply voltage, current draw, power factor, rated output. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Motor Efficiency Calculator work out the answer?
Efficiency = output power / input power x 100%. It applies the formula eff = Pout/Pin x 100 and shows the working so you can check each step by hand.
Is the Motor Efficiency Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.