Motor Power Requirement Calculator

Size motors from real loads and speeds. View power, current, energy, and charts using practical engineering assumptions today.

Calculator Input

Use realistic efficiency and service factors for safer motor selection.

Power Graph

Example Data Table

Application Method Load Input Main Motion Efficiency Estimated Input Power
Conveyor Drive Force and Velocity 900 N 1.8 m/s 88% 2.30 kW
Pump Coupling Torque and Speed 42 N·m 1450 rpm 91% 8.35 kW
Hoist Lift Lifting Load 150 kg 4 m in 8 s 86% 1.20 kW

Formula Used

1) Torque and speed: Mechanical shaft power equals torque multiplied by angular speed.

P = T × ω

Where ω = 2πN / 60, T is torque in newton metres, and N is rotational speed in rpm.

2) Force and velocity: Power equals force multiplied by linear velocity.

P = F × v

3) Lifting load: Power equals work divided by time.

P = mgh / t

Design motor power: After mechanical power is found, apply service, duty, and starting factors. Then divide by efficiency.

Motor Input Power = (Shaft Power × Service Factor × Duty Factor × Starting Factor) / Efficiency

How to Use This Calculator

  1. Select the calculation method that matches your machine.
  2. Enter load values such as torque, force, or lifted mass.
  3. Provide electrical details like voltage and power factor.
  4. Enter efficiency and application factors for design margin.
  5. Click the calculate button to view power and current.
  6. Review the graph and export the result as CSV or PDF.

Frequently Asked Questions

1. What does this calculator estimate?

It estimates shaft power, corrected design power, motor input power, horsepower, current, and hourly energy use. It helps you size a motor from motion and load data.

2. Which method should I choose?

Use torque and speed for rotating shafts. Use force and velocity for conveyors or linear motion. Use lifting load for hoists, winches, and vertical lifting systems.

3. Why is efficiency included?

Motors need more input power than the mechanical output because losses occur. Efficiency converts required shaft power into the electrical power the motor must draw.

4. What is service factor?

Service factor adds reserve capacity for real operating conditions. It helps account for overloads, wear, shock loading, and uncertainty in the actual duty profile.

5. Is the current estimate exact?

No. It is a practical estimate based on voltage, power factor, phase type, and calculated input power. Real current depends on the selected motor and control system.

6. Can I use this for hoists?

Yes. The lifting mode is suitable for hoists and elevators during steady lifting. Add realistic starting and service factors because lifting systems often need extra margin.

7. What units are used here?

This version uses SI units: newtons, metres, seconds, kilograms, volts, amperes, kilowatts, and horsepower. Keep every input in those units for correct results.

8. Should I choose the exact motor rating?

Usually you should select the next standard motor size above the result. That gives safer operation, better thermal margin, and improved reliability in variable conditions.

Validation Notes

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.