Horsepower (hp)
The horsepower (mechanical or imperial horsepower) is 550 foot-pounds of work per second, about 745.7 watts.
Convert horsepower to any power unit
1 horsepower = 745.6998716 watts
Quick facts
1 horsepower in other units
| Watts | 745.6998716 W |
| Kilowatts | 0.7456998716 kW |
| BTUs per hour | 2,544.433578 BTU/h |
| Megawatts | 0.000745699872 MW |
| Metric horsepower | 1.013869665 PS |
| Tons of refrigeration | 0.2120361315 TR |
| Gigawatts | 7.4569987 × 10-7 GW |
| Milliwatts | 745,699.8716 mW |
What is a horsepower?
The horsepower (mechanical or imperial horsepower) is 550 foot-pounds of work per second, about 745.7 watts. It is the usual unit for car and engine power in the US and UK. James Watt defined it in the 1780s from observations of mill horses so he could compare his steam engines with them.
Europe mostly uses the slightly smaller metric horsepower (PS or CV) of 735.5 W, and many countries now quote kilowatts.
Where the horsepower sits among power units
The horsepower is number 19 of 32 on our scale of power units, ordered from smallest to largest.
What horsepower are used for
- Car, motorcycle and boat engines
- Lawn mowers and power tools
- Electric motors in the US
Horsepower in real life
- A family car makes about 150–200 hp
- A Formula 1 car makes about 1,000 hp
- A person can sustain about 0.1 hp for a long time and briefly exceed 1 hp
Top horsepower conversions
Common amounts of horsepower
- 0.1 hp
- 0.2 hp
- 0.3 hp
- 0.4 hp
- 0.5 hp
- 0.6 hp
- 0.7 hp
- 0.8 hp
- 0.9 hp
- 1 hp
- 1.5 hp
- 2 hp
- 2.5 hp
- 3 hp
- 3.5 hp
- 4 hp
- 4.5 hp
- 5 hp
- 6 hp
- 7 hp
- 7.5 hp
- 8 hp
- 9 hp
- 10 hp
- 11 hp
- 12 hp
- 13 hp
- 14 hp
- 15 hp
- 16 hp
- 17 hp
- 18 hp
- 19 hp
- 20 hp
- 21 hp
- 22 hp
- 23 hp
- 24 hp
- 25 hp
- 26 hp
- 27 hp
- 28 hp
- 29 hp
- 30 hp
- 31 hp
- 32 hp
- 33 hp
- 34 hp
- 35 hp
- 36 hp
- 37 hp
- 38 hp
- 39 hp
- 40 hp
- 41 hp
- 42 hp
- 43 hp
- 44 hp
- 45 hp
- 46 hp
- 47 hp
- 48 hp
- 49 hp
- 50 hp
- 51 hp
- 52 hp
- 53 hp
- 54 hp
- 55 hp
- 56 hp
- 57 hp
- 58 hp
- 59 hp
- 60 hp
- 61 hp
- 62 hp
- 63 hp
- 64 hp
- 65 hp
- 66 hp
- 67 hp
- 68 hp
- 69 hp
- 70 hp
- 71 hp
- 72 hp
- 73 hp
- 74 hp
- 75 hp
- 76 hp
- 77 hp
- 78 hp
- 79 hp
- 80 hp
- 81 hp
- 82 hp
- 83 hp
- 84 hp
- 85 hp
- 86 hp
- 87 hp
- 88 hp
- 89 hp
- 90 hp
- 91 hp
- 92 hp
- 93 hp
- 94 hp
- 95 hp
- 96 hp
- 97 hp
- 98 hp
- 99 hp
- 100 hp
- 110 hp
- 120 hp
- 130 hp
- 140 hp
- 150 hp
- 160 hp
- 170 hp
- 180 hp
- 190 hp
- 200 hp
- 210 hp
- 220 hp
- 230 hp
- 240 hp
- 250 hp
- 260 hp
- 270 hp
- 280 hp
- 290 hp
- 300 hp
- 310 hp
- 320 hp
- 330 hp
- 340 hp
- 350 hp
- 360 hp
- 370 hp
- 380 hp
- 390 hp
- 400 hp
- 410 hp
- 420 hp
- 430 hp
- 440 hp
- 450 hp
- 460 hp
- 470 hp
- 480 hp
- 490 hp
- 500 hp
- 600 hp
- 700 hp
- 800 hp
- 900 hp
- 1,000 hp
- 1,200 hp
- 1,500 hp
- 2,000 hp
- 2,500 hp
- 3,000 hp
- 4,000 hp
- 5,000 hp
- 10,000 hp
Convert horsepower to all 31 other units
Metric (SI)
Horsepower
Heat & refrigeration
Mechanical & other
Convert to horsepower
Frequently asked questions
What is a horsepower?
The horsepower (mechanical or imperial horsepower) is 550 foot-pounds of work per second, about 745.7 watts.
How is the horsepower defined?
550 foot-pounds per second (about 745.7 W).
How many watts are in a horsepower?
One horsepower equals 745.6998716 watts.
How many kilowatts are in a horsepower?
One horsepower equals 0.7456998716 kilowatts.
How many BTUs per hour are in a horsepower?
One horsepower equals 2,544.433578 BTUs per hour.