Thread Starter


someone recently asked me what was the horsepower rating on the motor i used. i didn't know the answer. I do know the torque contant (0.23 Nm/A), stall current (20A), no load speed (5600 rpm), etc. What is the equation I need to use to get horse power of the motor, and what parameters do I need?
Hi, you can use the following formula:

HP = 1.341*KW

to get the W = volt*amp.

and kw is = 1000 watt.

Tony Moscioni

1 horsepower = 746 watts
1 horsepower = .746 kilowatts
1 horsepower = 550 ft-lbs/sec
1 horsepower = 33000 ft-lbs/min
1 horsepower hr. = 2545 Btu
1 kilowatt hr. = 3412 Btu
1 hp = 746 watts, so if you have your motor's mechanical output power in watts or kw, just convert directly.

In general, POWER = RPM * TORQUE * 2 * pi / CONVERSION FACTOR. In US units, HP = RPM * FT-LBS * 2 * PI /33,000. Since you are looking for a result in US units, maybe you could convert your full-load torque to ft-lbs and use this formula.
The RPM and TORQUE that you use in the equation below should come from the upper right hand corner of the speed-torque curve. Using the data sheet values may overstate the HP. Using the speed-torque curve, you can calculate the continuous HP rating as well as the limited duty rating. Good luck.