Supported units
- Watt (W)
- Kilowatt (kW)
- Megawatt (MW)
- Mechanical horsepower (hp)
Conversion tool
Power Converter
Select a category, enter a value, and convert between compatible units.
Power units explained
Power is the rate at which energy is transferred or work is performed. One watt equals one joule per second, while kilowatts and horsepower are common equipment ratings.
Common engineering uses
Power conversion is used for motors, engines, electrical equipment, pumps and heating or cooling systems.
Formula
P = E / t
Power is the rate at which energy is transferred or work is performed. One watt equals one joule per second. For rotating machinery, power can also be calculated from torque and angular speed.
- P = power, measured in watts (W)
- E = transferred energy, measured in joules (J)
- t = elapsed time, measured in seconds (s)
Common conversions
| From | Equivalent value |
|---|---|
| 1 kilowatt (kW) | 1,000 watts (W) |
| 1 megawatt (MW) | 1,000 kilowatts (kW) |
| 1 mechanical horsepower (hp) | approximately 745.700 watts (W) |
| 1 metric horsepower (PS) | approximately 735.499 watts (W) |
| 1 kilowatt (kW) | approximately 1.34102 mechanical hp |
| 1 BTU per hour (BTU/h) | approximately 0.293071 watts (W) |
Convert 15 kW to mechanical horsepower
- Use the relationship 1 kW = 1.34102 mechanical hp.
- Multiply 15 by 1.34102.
- 15 × 1.34102 = 20.1153 hp.
15 kW ≈ 20.12 mechanical hp
Mechanical horsepower and metric horsepower use different definitions. Check which horsepower unit appears in the original equipment specification.
Engineering applications
- Comparing motor and engine ratings across metric and imperial specifications.
- Selecting pumps, fans and compressors for fluid systems.
- Calculating electrical loads and equipment demand.
- Evaluating heating and cooling equipment rated in watts, kilowatts or BTU/h.
- Estimating machinery performance and energy use over time.
Common mistakes
- Confusing power with energy. A power rating does not state how much energy is used until operating time is included.
- Using mechanical horsepower and metric horsepower as if they were identical.
- Comparing electrical input power directly with mechanical output power without accounting for efficiency.
- Comparing peak power with continuous rated power.
- Applying a single-phase electrical formula to a three-phase system, or ignoring power factor.
Frequently asked questions
How many watts are in one kilowatt?
One kilowatt equals exactly 1,000 watts.
How many horsepower are in one kilowatt?
One kilowatt is approximately 1.34102 mechanical horsepower, or 1.35962 metric horsepower.
What is the difference between hp and PS?
Mechanical horsepower is approximately 745.700 W. Metric horsepower, often marked PS, is approximately 735.499 W.
Is a higher power rating always more efficient?
No. Power describes a rate of energy transfer. Efficiency compares useful output with required input.
Can power be calculated from torque?
Yes. For rotating systems, power equals torque multiplied by angular speed, provided consistent units are used.