Convert power units — watts, kilowatts, horsepower, BTU/hr.
| Unit | Name | Value |
|---|---|---|
| W | Watt | 745.7 |
| kW | Kilowatt | 0.7457 |
| MW | Megawatt | 0.0007457 |
| BTU/hr | BTU/hr | 2544.4346 |
Formula: Watt = Horsepower × 745.7
Multiply any horsepower value by 745.7 to get watt.
Reverse: Horsepower = Watt × 0.001341
Common horsepower values — factor: 1 hp = 745.7 W
| Horsepower (hp) | Watt (W) | Context |
|---|---|---|
| 0.1 hp | 74.57 W | Small motor |
| 0.5 hp | 372.9 W | Half hp pump |
| 1 hp | 745.7 W | 1 hp motor |
| 5 hp | 3,728 W | 5 hp outboard |
| 10 hp | 7,457 W | 10 hp motor |
| 50 hp | 3.728e+04 W | Small car engine |
| 100 hp | 7.457e+04 W | Compact car |
| 150 hp | 111,900 W | Mid-range car |
| 200 hp | 149,100 W | Performance car |
| 300 hp | 223,700 W | Sports car |
| 500 hp | 372,800 W | Supercar |
| 1,000 hp | 745,700 W | Race car |
| 1e+04 hp | 7,457,000 W | Jet engine fraction |
| 100,000 hp | 74,570,000 W | Large ship engine |
| 1,000,000 hp | 745,700,000 W | Power plant fraction |
hp × 745.7 = W.
1 hp = 745.7 W. 100 hp = 74,570 W = 74.57 kW.
W ÷ 745.7 = hp.
Rates car engine output in horsepower for marketing and performance comparison.
Specifies boat and ship engine power in horsepower for propulsion system design.
Rates pump motor size in horsepower for industrial and agricultural applications.
Sizes compressor motors in horsepower for commercial refrigeration systems.
Compares vehicle performance and evaluates engine modifications in horsepower.
Selects motors and compressors based on horsepower ratings in US specifications.
Horsepower (hp) was defined by James Watt in the 1780s to quantify steam engine output in terms familiar to mine operators who used horses to pump water. One mechanical horsepower equals 550 foot-pounds per second = 745.7 watts.
Horsepower remains the dominant power rating for vehicle engines in the United States, Canada, and the UK. Car engines range from 70 hp (economy) to 700+ hp (sports cars). Electrical motors, pumps, and industrial equipment are often rated in both kW and hp.
Interesting fact: There are multiple horsepower definitions: mechanical hp (745.7 W), metric hp (735.5 W), electrical hp (746 W), and boiler hp (9,810 W). Most automotive usage refers to mechanical hp. A racehorse at full gallop produces about 14–15 hp peak, not 1 hp.
The watt (W) is the SI unit of power, defined as one joule per second. It was named after James Watt, the Scottish inventor whose improvements to the steam engine in the 1760s–1780s powered the Industrial Revolution. The unit was officially adopted by the Second Congress of the British Association for the Advancement of Science in 1882.
Watts define the power consumption of all electrical devices: a phone charger draws 5–20W, a laptop 30–65W, a microwave 800–1200W. Electrical utility systems worldwide are rated and billed based on watts and kilowatts.
Interesting fact: James Watt himself coined the term 'horsepower' to market his steam engines to mine owners — he defined it as the power needed to lift 33,000 pounds one foot in one minute. The watt was named in his honor a century after his death.
Converting horsepower to watt is common across electrical engineering, automotive, and HVAC industries. Different sectors use different power units — watts and kilowatts in electrical systems, horsepower in automotive and industrial machinery, and BTU/hr in heating and cooling — making accurate conversion essential for international equipment specifications and cross-disciplinary engineering.
Quick reference: 5 hp = 3728 W and 10 hp = 7457 W. Reverse: 1 W = 0.001341 hp. Exact factor: 1 hp = 745.7 W.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.