Watts to HP Calculator

One horsepower is about 746 watts, so to convert watts to horsepower you divide the wattage by 745.7, the mechanical horsepower value used in the United States.

The divisor is 745.7 because that is how many watts make one mechanical horsepower, the value usually rounded to 746 W. For the reverse direction, our HP to Watts calculator multiplies instead.

Does 1 hp mean 746 watts?

Yes, near enough. One mechanical horsepower is 745.7 W, which rounds to 746 W, and electric horsepower is exactly 746 W. So a device rated at 746 W is a 1 hp device. Metric horsepower (PS) is a little lower at 735.5 W, the value used for European engines, but for US work 746 W is 1 hp.

Is 750 watts equal to 1 hp?

Almost exactly. One mechanical horsepower is 745.7 W, so 750 W works out to 1.01 hp, just over one. The round figure of 746 W (electric horsepower) is 1.00 hp on the nose. So a 750 W motor is treated as a 1 hp motor for practical purposes, which is why 750 W is the ceiling for a 1 hp class electric-bike motor in many places.

The three horsepower definitions

The divisor depends on which horsepower you want.

Mechanical horsepower is the US default, so use it unless you know a figure is metric. The three values are the standard ones in the NIST guide to SI units.

Watts to HP conversion chart

These use mechanical horsepower (W / 745.7), the US default. The small wattages line up with common small-motor and e-bike classes.

To convert any wattage, divide it by 745.7. A 2,000 W motor is 2,000 / 745.7 = 2.68 hp, and a 5,000 W motor is 6.71 hp. The calculator returns all three horsepower types from the wattage you enter.

Small motors: 250 W, 500 W, and 750 W

Small electric motors cluster around a few common wattages. A 250 W motor is 0.34 hp, a 500 W motor is 0.67 hp, and a 750 W motor is 1.01 hp, which is why 750 W is the legal ceiling for a 1 hp class e-bike motor in many jurisdictions. Larger US motors are rated in horsepower under NEMA MG 1, and that rating is the shaft output, so a watt figure taken from a nameplate is the mechanical output, not the electrical draw.

Watts to hp for a motor or pump

Reading a motor the other way, its wattage is the mechanical output, so dividing by 745.7 gives the horsepower rating. If you measured the electrical input watts at the plug instead, the horsepower you get is higher than the motor true output, because some of that input is lost to inefficiency. A pool or well pump labeled 1 hp may draw 1,500 W at the wall, yet its true output is closer to 746 W once efficiency is counted. When you compare pumps, use the horsepower from the rated output, not the input wattage. To find the current a motor draws, convert its watts to amps with our Watts to Amps calculator.

Watts to bhp and the kilowatt version

Brake horsepower (bhp) uses the mechanical horsepower value, so watts to bhp is the same division by 745.7: a 3,000 W output is about 4.02 bhp. If your figure is in kilowatts rather than watts, our kW to HP calculator does the conversion at the kilowatt scale, where 1 kW is 1.34 hp.

Limitations and safe use

The horsepower from a watt figure is only as good as the watt figure. A nameplate output in watts converts exactly; a wall measurement includes the motor inefficiency and reads high in horsepower. For a motor, size the circuit from its full-load current per NEC Article 430 and the nameplate, not from watts or the converted hp, and allow for the service factor and starting inrush. This tool converts the power rating only, not a substitute for a circuit design by a qualified electrician.