Horsepower to Watts (hp to W)
1 hp = 745.7 W
To convert horsepower to watts: watts = hp × 745.7
| horsepower | watts |
|---|---|
| 0.25 hp | 186.4 W |
| 0.33 hp | 246.1 W |
| 0.5 hp | 372.8 W |
| 0.75 hp | 559.3 W |
| 1 hp | 745.7 W |
| 1.5 hp | 1,119 W |
| 2 hp | 1,491 W |
| 3 hp | 2,237 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.
Comparing a US and a European spec sheet? Torque needs converting too: ft-lbs to Nm multiplies by 1.355818.
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.