Watts to HP Converter
Convert watts to mechanical horsepower — 745.7 watts to the horsepower. 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 hp 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) |
| 250 W | 0.3353 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) |
| 2,000 W | 2.682 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) |
| 100,000 W | 134.1022 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 watts in a horsepower?
745.7 for mechanical horsepower.
What about metric horsepower?
The PS is 735.5 watts, slightly less.
How powerful is a person?
A fit cyclist sustains about 250 W, roughly a third of a horsepower.
Is a horse really one horsepower?
A real horse can peak far above it; Watt set the figure from sustained work to sell engines against horses.
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.