Watts to Horsepower Converter
Convert watts to mechanical horsepower — divide by 745.7. Results update as you type; exact factors shown.
One watt is 0.0013 horsepower (mechanical) — see the exact factor, not a rounded rule of thumb.
How the watts to horsepower converter works
Power converts through the watt. Mechanical horsepower is 550 ft·lbf/s = 745.6999 W; metric horsepower (PS, used in European car specs) is 735.4988 W. Air-conditioner capacities are quoted in kW, BTU/h (1 W = 3.412 BTU/h) or tons of refrigeration (3.517 kW).
The US uses customary units (US gallon, short ton, °F) in daily life; NIST SP 811 gives the exact SI factors.
Common power conversions
| From | To | Units |
|---|---|---|
| 100 W | 0.1341 hp | watts to horsepower (mechanical) |
| 500 W | 0.6705 hp | watts to horsepower (mechanical) |
| 745.7 W | 1 hp | watts to horsepower (mechanical) |
| 1,000 W | 1.341 hp | watts to horsepower (mechanical) |
| 5,000 W | 6.7051 hp | watts to horsepower (mechanical) |
| 10,000 W | 13.4102 hp | watts to horsepower (mechanical) |
| 50,000 W | 67.0511 hp | watts to horsepower (mechanical) |
| 74,570 W | 100 hp | watts to horsepower (mechanical) |
| 100,000 W | 134.1022 hp | watts to horsepower (mechanical) |
| 150,000 W | 201.1533 hp | watts to horsepower (mechanical) |
| 200,000 W | 268.2044 hp | watts to horsepower (mechanical) |
| 500,000 W | 670.511 hp | watts to horsepower (mechanical) |
Units in this converter and their exact factors
| Unit | Symbol | One unit in watts |
|---|---|---|
| watt | W | 1 watt |
| kilowatt | kW | 1,000 watt |
| megawatt | MW | 1,000,000 watt |
| horsepower (mechanical) | hp | 745.6998715823 watt |
| metric horsepower (PS) | PS | 735.49875 watt |
| BTU per hour | BTU/h | 0.29307107 watt |
| ton of refrigeration | TR | 3,516.8528421 watt |
FAQFrequently asked questions about power conversion
How many horsepower is 1 kW?
1.341 hp.
What is 100 kW?
134 hp.
Which horsepower does a car use?
US and UK specs use mechanical hp; continental Europe uses PS, which reads about 1.4% higher for the same engine.
What is a person's sustained output?
About 100 W, or 0.13 hp. A trained cyclist holds 300 to 400 W for an hour.
What is 745.7 W?
Exactly one horsepower.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Institute of Standards and Technology (NIST) — United States's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.