How to Convert Horsepower to Watts (hp to W)
Power conversions help compare car engines in hp and kW, and air-con units rated in BTU/h against their electrical draw in watts. This guide shows how to convert horsepower into watts by hand, with examples and a quick-reference table.
The conversion
To convert horsepower to watts, multiply the value by 745.699872. To go the other way, divide by the same number (or multiply by 0.0013410221). For a quick estimate, multiply by about 750.
Watts = horsepower × 745.699872
Worked examples
- 3 hp = 2,237.1 W
- 12.5 hp = 9,321.25 W
- 75 hp = 55,927.49 W
Horsepower to Watts table
| Horsepower | Watts |
|---|---|
| 1 hp | 745.6999 W |
| 2 hp | 1,491.4 W |
| 5 hp | 3,728.5 W |
| 10 hp | 7,457 W |
| 20 hp | 14,914 W |
| 25 hp | 18,642.5 W |
| 50 hp | 37,284.99 W |
| 100 hp | 74,569.99 W |
| 250 hp | 186,424.97 W |
| 500 hp | 372,849.94 W |
| 1,000 hp | 745,699.87 W |
Common questions
Is hp to W exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Watts to Horsepower converter.
Mistakes to avoid
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Background
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
For any value, use the Horsepower to Watts Converter or browse all power converters.
Run your own numbers: Horsepower to Watts Converter