Power Converter

Convert between watts, kilowatts, horsepower, BTU/h, and other power units in seconds. Enter a value for instant conversions in electrical, mechanical, and HVAC work.

How to Use

  1. Enter the power value

    Type the power value you want to convert.

  2. Select the units

    Choose the source unit (e.g., kW) and the target unit (e.g., HP).

  3. View the result

    Click Convert to see the converted power value.

What Is Power?

Power is the amount of energy transferred or consumed per unit of time, in other words how 'fast' energy is being used. The base unit in the SI system is the watt (W), where 1 W means consuming 1 joule (J) of energy per second.

Different units by field

  • Electrical: watts (W), kilowatts (kW), megawatts (MW)
  • Mechanical and automotive: horsepower (hp) — used to rate engine and motor output
  • HVAC: BTU/h, kW — air conditioner and boiler capacity
  • Thermodynamics: calories per second (cal/s)

This converter uses the watt as its base, converting every unit through it, so you can compare power specifications from completely different fields at a glance.

Calculation Formula

Every unit is first converted to the base unit, the watt (W), and then divided by the factor of the target unit.

result = value × (source factor) ÷ (target factor)

Watt conversion factors for each unit: W=1, kW=1000, MW=1000000, mechanical hp=745.7, electrical hp=746, BTU/h=0.293071, cal/s=4.184.

Example: 1 kW to mechanical horsepower

1 × 1000 ÷ 745.7 = 1.341 hp

So 1 kilowatt is about 1.341 mechanical horsepower. Conversely, a 100 hp engine equals 100 × 745.7 ÷ 1000 = 74.57 kW.

Frequently Asked Questions

What is the relationship between watts (W) and horsepower (hp)?
The watt (W) is the SI unit of power, while horsepower (hp) is a traditional power unit. One mechanical horsepower is about 745.7 W, and it is mainly used to describe the output of engines and motors.
How do mechanical and electrical horsepower differ?
Mechanical horsepower is about 745.7 W, the traditional unit defined by James Watt. Electrical horsepower is defined as exactly 746 W and is used for rating electric motors. The difference between the two values is only about 0.04%, which is very small.
What is BTU/h?
BTU/h (British Thermal Unit per hour) is a unit that expresses the amount of heat energy transferred per hour. One BTU/h is about 0.293071 W, and it is mainly used to rate the capacity of heating and cooling equipment.
Are kW and kWh different?
Yes. kW (kilowatt) is a unit of power (the rate at which energy is used), while kWh (kilowatt-hour) is a unit of energy. Running a 1 kW device for one hour consumes 1 kWh. This converter handles only power (W, kW, hp, etc.) and does not convert kWh.
What unit is used for air conditioner cooling capacity?
Air conditioner cooling capacity is expressed in BTU/h or kW. Since 1 kW is about 3,412 BTU/h, a 7,000 kcal class air conditioner, for example, corresponds to about 8.14 kW, or roughly 27,800 BTU/h.
How are calories per second (cal/s) converted to watts?
One cal/s equals exactly 4.184 W. The calorie is a unit of heat, so calories per second express the rate of heat transfer (thermal output). It is used to rate the thermal output of boilers and heat exchangers.
Why is the conversion result shown to six decimal places?
Unit conversion uses factors close to irrational values, such as 745.7 or 0.293071, so rounding errors occur. This calculator rounds at six decimal places to ensure sufficient precision even for BTU/h and horsepower conversions.
How many watts is a 1 horsepower car engine?
On a mechanical horsepower basis, 1 hp = 745.7 W. Therefore a 200 hp car produces 200 × 745.7 = about 149,140 W of output, that is roughly 149.1 kW.
2026 international standards

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