Power Converter

By Suraj GiriUpdated 24 September 2026

This page converts a power from one unit into another. Every value passes through the watt, the SI unit power is held in, and power stays power: a unit only converts inside its own dimension.

How do you convert power between watts, kilowatts and horsepower?

Pick the unit you have, pick the unit you want, and type the value. The page multiplies by the factor between the two and prints the arithmetic under the result, so the answer and the working are the same object.

1. Choose the unit your value is in. This page opens on the horsepower (mechanical).
2. Choose the unit you want it in. This page opens on the kilowatt.
3. Type the value, or the value with its units, such as 100 hp to kW. The result and the factor behind it appear together.
4. Read the working. It converts into the watt first and out again, which is the same two lines you would write by hand.

Watts, kilowatts and horsepower measure power, not energy, so for kilowatt-hours or any other quantity, start from the measurement unit converter.

Power Conversion Table

One row per unit this page offers, each measured against the watt. The last column says whether the factor is a definition or a reading of one.

Worked Examples

The question the bank ranked highest for this page, answered with the working.

Common Power Conversions

Each US customary or imperial unit on this page against the metric unit nearest it in size, both ways. Exact values print in full; the rest are rounded to 10 significant figures. Select one to load it into the converter.

• 1 hp = 1.013869665 PS
• 1 PS = 0.9863200706 hp
• 1 Btu_IT/h = 0.2930710702 W
• 1 W = 3.412141633 Btu_IT/h

Where These Factors Come From

Every factor above is read from the knowledge base rather than typed for the page, and every result is worked from those factors. These are the statements it holds for power.

• One watt is one joule per second. Mechanical horsepower is 550 foot-pounds-force per second, which is 745.6998715822702 W; metric horsepower is 75 kilogram-force metres per second, which is exactly 735.49875 W.
• An exact factor is a definition rather than a measurement. 1 in = 25.4 mm and 1 lb = 0.45359237 kg were fixed by the 1959 international yard and pound agreement, so they never gain another digit.
• One joule is one newton metre, the work done moving one newton through one metre. One kilowatt-hour is exactly 3.6 MJ.
• standard acceleration of free fall, value 9.80665
• How this page reports a result result in the target power unit; the horsepower variant is named, mechanical or metric

SI prefixes on this page

Which Horsepower?

Mechanical horsepower and metric horsepower are different units with different definitions, and a figure quoted in horsepower means nothing until it says which. Both are listed here as separate units, and the result names the one it used.

• A kilowatt is a rate and a kilowatt-hour is an amount, so a power figure turns into an energy figure only once a time is attached.
• BTU per hour is a unit of power; a BTU on its own is energy.

The rule behind this factor is the same for every unit - base units and derived units.

Frequently Asked Questions

Related Conversions

• Energy sits in the same measurement group as power - convert energy between joules and kilowatt-hours.
• If you are measuring electric current rather than power, convert a current between amps and kiloamps instead.
• If you are measuring voltage rather than power, convert a voltage between volts and kilovolts instead.
• If you are measuring apparent power rather than power, convert apparent power between VA and kVA instead.
• If you are measuring torque rather than power, force applied at a distance from the axis instead.
• If you are measuring illuminance rather than power, convert a light level between lux and foot-candles instead.

The rest of the family sits on pick another quantity to convert.