What is horsepower (hp)?

December 17, 2012

What is horsepower? How do I calculate my horsepower? These are common questions we receive from our customers. To answer this question, let’s first define what horsepower is.

what is horsepower watts to horsepower conversion equationHorsepower, like any unit of power, is simply a rate at which work is being done. Literally, the horsepower unit originates from an experiment which set out to measure the power of a single horse. It was determined that a horse is capable of performing 33,000 ft-lbf of work per min. We will address to this number later in the explanation.

First, a few equations to help you calculate your horsepower:

what is horsepower motor calculation HP



So –

what is horsepower hp equation horsepower specs



For electric motors, power or horsepower can be calculated from the torque and speed. For example, if you have a motor rated for 3,000 RPM and 6 in-lbf then the horsepower is calculated below.

what is horsepower hp calculate motor horse power



63,025 is a constant when using RPM for speed and in-lbf for torque units. 5,252 is another common constant if the speed is in RPM and torque is in ft-lbf. If the units are different then simply make the unit conversion.

The derivation of these constants is done using the 33,000 ft-lbf /min = 1 horsepower. Though horsepower units are a derivative of the 33,000 ft-lbf/min, it is not critical to understanding how to calculate motor horsepower for speed and torque.

Another common unit of power that motors are rated in is watts. The conversion from watts to horsepower is 745.7 watts = 1 hp.

To assist designers with sometimes difficult unit conversions Groschopp has developed The MOTORTEC™ STP calculator, a free, downloadable program that provides a fast, easy way to calculate speed, torque, or power. Conversions of the most commonly used units are selectable, automatically generated and can be printed out.

  • Calculate Speed, Torque and Power
  • Calculate Estimated Electrical Current and Losses for Optimum Motor Selection
  • Easily and Accurately Convert Units of Measurement
  • Customizable, Printed Report Function
  • Calculate Operating Costs

How to use the Motor Search Tool

Narrow your search by selecting motor type, gearbox, voltage, and phase options for your desired motor.

Select a dominant variable: choose one of the three parameters to narrow your search. The selected variable determines which slider bar you will be able to manually move.

Use the slider corresponding to your dominant variable to further narrow your motor selection. The other sliders will automatically move to show available ranges based on the range of your selected variable.

Results will upload as your search criteria changes. If you have any questions regarding your results or how to use the search tool, you can chat with us using the green tab on the left-hand side of your screen.

Note: Groschopp Universal motors are custom built to fit your application so no additional options are available to narrow the search. Selecting the Universal motor type will prompt a message taking you to the Universal product page.

Not sure what you need?

One of our team members would be happy to help. Contact us at 800-829-4135 or by email at sales@groschopp.com. You can also chat with us using the green tab on the left side of your screen.

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Universal Motors

Groschopp Universal motors are custom built to fit your application so no additional options are available to narrow the search. Standard frame sizes and motor features can be found on the Universal page.

go to Universal page