Horsepower to Watts (hp to W)
Multiply horsepower by 745.7 to get watts, or by 0.7457 to get kilowatts. The factor comes from James Watt's definition of one horsepower as 550 foot-pounds per second (NIST SP 811: 745.699872 W).
Formula
watts = hp × 745.7
Example: 0.75 horsepower = 559.275 watts.
Horsepower to Watts chart
| horsepower | watts |
|---|---|
| 0.25 | 186.425 |
| 0.33 | 246.081 |
| 0.5 | 372.85 |
| 0.75 | 559.275 |
| 1 | 745.7 |
| 1.5 | 1,118.55 |
| 2 | 1,491.4 |
| 3 | 2,237.1 |
| 5 | 3,728.5 |
| 10 | 7,457 |
| 25 | 18,642.5 |
| 50 | 37,285 |
| 100 | 74,570 |
| 200 | 149,140 |
| 300 | 223,710 |
| 500 | 372,850 |
Good to know
Motor nameplates: a ½ hp garbage-disposal or pump motor delivers about 373 W of mechanical output, and typically draws more electrical power than that because of losses. Sizing a generator or inverter needs the electrical input plus the extra current a motor takes to start.
Car engines: multiply hp by 0.7457 for the kW figure used in European and Asian specifications. A 300 hp engine is 224 kW.
Frequently asked questions
How many watts is 1 horsepower?
745.7 watts (mechanical horsepower).
How many kW is 100 hp?
100 hp is 74.57 kW.
How many watts is a 1/2 hp motor?
A ½ hp motor delivers about 373 W of mechanical power.