The power units
- Watt (W), kilowatt (kW) and megawatt (MW) are the SI units. One watt is one joule per second.
- Horsepower (hp) is defined as 550 foot-pounds per second, which is 745.69987 W.
- Metric horsepower (PS) is 75 kilogram-force meters per second, exactly 735.49875 W, about 1.4 percent less than hp.
- BTU per hour (BTU/h) is the international table BTU of 1,055.05585 joules per hour, about 0.2931 W. The BTU calculator finds the air conditioner size a room needs.
- Kilocalorie per hour uses the thermochemical kilocalorie of 4,184 joules, about 1.162 W.
The factors follow NIST Special Publication 811, Appendix B.
Common power conversions
| From | Equals |
|---|---|
| 1 kilowatt | 1.34102209 horsepower |
| 1 horsepower | 0.7456998716 kilowatts |
| 1 kilowatt | 1.359621617 metric horsepower |
| 1 metric horsepower | 0.9863200706 horsepower |
| 1 horsepower | 745.6998716 watts |
| 1 BTU per hour | 0.2930710702 watts |
| 1 kilowatt | 3,412.141633 BTU per hour |
Kilowatts to horsepower
| Kilowatts (kW) | Horsepower (hp) |
|---|---|
| 1 | 1.341 |
| 5 | 6.7051 |
| 10 | 13.41 |
| 50 | 67.051 |
| 75 | 100.58 |
| 100 | 134.1 |
| 110 | 147.51 |
| 150 | 201.15 |
| 200 | 268.2 |
| 250 | 335.26 |
| 300 | 402.31 |
| 400 | 536.41 |
| 500 | 670.51 |
How the conversion works
All power units are fixed multiples of the watt, so each conversion is one multiplication. To go from kW to hp, multiply by 1,000 and divide by 745.69987, which is the same as multiplying by 1.34102. From hp to kW, multiply by 0.7457. To turn the watts of an appliance into a running cost, use the electricity cost calculator.
How to use it
- 1Pick the unit you have on the left and the one you want on the right. kW to hp is set up when the page opens.
- 2Type the value. Either side accepts input, and swap turns the conversion around.
- 3Read the result and see the same power in every other unit in the list. Copy the number or a link.
Frequently asked questions
How many horsepower is 1 kW?
About 1.341 horsepower. One horsepower is 745.7 watts, so divide the watts by 745.7, or multiply kilowatts by 1.341.
What is the difference between hp and PS?
Horsepower (hp) is defined as 550 foot-pounds per second, about 745.7 W. Metric horsepower (PS) is 75 kilogram-force meters per second, exactly 735.49875 W. So 100 PS is about 98.6 hp.
How many watts is 1 horsepower?
About 745.7 watts. Metric horsepower is a little smaller, 735.5 watts.
How do I convert BTU per hour to kW?
Multiply by 0.000293071, or divide by about 3,412. A rating of 12,000 BTU per hour is about 3.52 kW.