Motor Horsepower Calculator

Estimate motor horsepower from amps, volts, watts, kilowatts, torque, RPM, phase type, efficiency, and power factor. This calculator also estimates input power, output power, full-load amps, torque, kVA, and motor load values.

Calculate Motor Horsepower

Horsepower = output watts ÷ 746. Output watts can be estimated from volts, amps, efficiency, and power factor.
Your result will appear here.

How the motor horsepower calculator works

Electrical input:
The calculator estimates input watts from volts, amps, phase type, and power factor.

Motor output:
Efficiency is applied to estimate output watts, then output watts are converted to horsepower.

Mechanical input:
Torque and RPM can also be used to estimate mechanical horsepower directly.

Why use a motor horsepower calculator?

A motor horsepower calculator helps estimate motor size from electrical readings or mechanical torque and speed.

It can help with pumps, fans, compressors, conveyors, shop tools, HVAC motors, replacement planning, and general motor load estimates.

What your result means

Your result shows estimated horsepower, output watts, output kilowatts, input watts, input kilowatts, estimated amps, torque estimate, kVA, efficiency, power factor, and comparison motor estimates.

Motor horsepower calculator formulas

Frequently asked questions

How do I calculate motor horsepower?

Estimate output watts, then divide by 746. Output watts can be found from electrical input watts multiplied by motor efficiency.

How many watts are in one horsepower?

One horsepower is about 746 watts.

Can I calculate horsepower from torque and RPM?

Yes. For torque in pound-feet, multiply torque by RPM, then divide by 5,252.

Should I use calculated HP or nameplate HP?

For real equipment decisions, use the motor nameplate and manufacturer data. Calculated horsepower is useful for planning and estimating.