Quick example
Convert 1 mechanical horsepower to kilowatts
Mechanical horsepower is defined as 550 foot-pounds force per second. Converting that rate to SI units gives approximately 745.699871582 watts, or 0.745699871582 kilowatts.
Quick reference
Common power conversions
| Starting power | Equivalent |
|---|---|
| 1 W | 1 J/s |
| 1 kW | 1,000 W |
| 1 MW | 1,000 kW |
| 1 hp (mechanical) | 745.699872 W |
| 1 PS (metric) | 735.49875 W |
| 1 kW | 1.34102 hp |
| 1 kW | 1.35962 PS |
| 1 kW | 3,412.14 BTU/h |
Unit definitions
Electrical, mechanical, and heating power
Watts, kilowatts, and megawatts
The watt is the SI power unit and equals one joule per second. A kilowatt is 1,000 watts, and a megawatt is 1,000 kilowatts.
Mechanical horsepower
Mechanical horsepower, shown as hp, is defined as 550 foot-pounds force per second and equals approximately 745.699872 watts.
Metric horsepower
Metric horsepower, shown as PS, is based on 75 kilogram-force meters per second and equals exactly 735.49875 watts.
BTU/h and ft⋅lbf/s
BTU per hour is common in heating and cooling; this tool uses the International Table BTU. Foot-pound force per second is a mechanical rate of work.
Power versus energy
Power is a rate, not an energy total
Watts and horsepower measure how quickly energy is transferred. Watt-hours and kilowatt-hours measure the total energy transferred over time, so converting between power and energy requires a duration. Signed power values can represent direction, such as consumption versus regeneration; a negative sign does not mean negative capacity.
Common questions
Power conversion FAQ
How many kilowatts are in one horsepower?
One mechanical horsepower equals approximately 0.745699872 kilowatts.
How many horsepower are in one kilowatt?
One kilowatt equals approximately 1.341022 mechanical horsepower.
What is the difference between mechanical and metric horsepower?
Mechanical horsepower is approximately 745.699872 watts; metric horsepower is 735.49875 watts. Mechanical horsepower is about 1.4 percent larger.
How many BTU per hour are in one kilowatt?
One kilowatt equals approximately 3,412.1416 International Table BTU per hour.
What is the difference between watts and watt-hours?
Watts measure power, or the rate of energy transfer. Watt-hours measure the total energy transferred over time.