Power Converter

Related Calculators

Table of contents

• How to use
• Common mistakes
• Definitions
• Methodology
• Limitations & assumptions
• Sources

Power value: The starting number you want to convert.

Convert from: The unit your starting value is already in.

Watt (W): A standard SI unit of power, meaning the rate of energy transfer.

Kilowatt (kW): 1,000 watts.

Megawatt (MW): 1,000,000 watts.

Microwatt (uW): One-millionth of a watt.

Milliwatt (mW): One-thousandth of a watt.

Horsepower, mechanical: A common US horsepower definition, not exactly the same as other horsepower types [2].

Horsepower, electric: A separately defined horsepower unit used in some electrical contexts.

Horsepower, metric (PS): A metric horsepower unit, often written as PS.

Boiler horsepower (bhp): A much larger power unit used for boiler output.

Btu per hour (Btu/h): A thermal power unit often used in heating and cooling.

Kilocalorie per hour (kcal/h): Power expressed as kilocalories each hour.

Decimal places: How many digits are shown after the decimal point in results.

Mistake: Leaving Power value blank or entering text like "ten".
Fix: Enter a numeric value such as 10, 100, or 2.5.

Mistake: Picking the wrong option in Convert from and using generic horsepower by accident.
Fix: Match the exact label, such as Horsepower, mechanical , Horsepower, electric , Horsepower, metric , or Boiler horsepower .

Mistake: Thinking Horsepower, mechanical and Horsepower, electric should give the same result.
Fix: Compare the separate output rows and keep the horsepower type with the value whenever you copy it.

Mistake: Reading a rounded display as an exact value when Decimal places is set low.
Fix: Increase Decimal places to 4 or 6 if small unit differences matter.

Mistake: Confusing Btu per hour with energy instead of power.
Fix: Use the Btu per hour row only as a rate of power, and compare it with Watts or Kilowatts .

Mistake: Assuming a negative value in Watts or Converted value is automatically wrong.
Fix: Negative power can be valid in signed systems; read the Note output to interpret the sign in your context.

• The calculator converts by fixed unit definitions, so it does not account for equipment efficiency, losses, or operating conditions.
• Horsepower values depend on the exact horsepower type selected. Using the wrong horsepower definition changes the result.
• Displayed values are rounded to the chosen Decimal places, even though the calculator keeps higher internal precision before rounding.
• Very large or very small values can be harder to read, even when the math is correct.
• Negative inputs are allowed because signed power can be meaningful in some systems, but many everyday device ratings are shown as positive values only.
• The main Converted value is a convenience pairing for quick reading. The full set of output rows is the more complete view.

How the conversion works

The calculator first turns your starting value into watts, then converts that watt value into every other shown unit. This keeps the math consistent across all outputs.

P_W = input value x factor to watt(from unit)

P_target = P_W / factor to watt(target unit)

Conversion factors used

1 uW = 0.000001 W

1 mW = 0.001 W

1 kW = 1000 W

1 MW = 1000000 W

1 hp (mechanical) = 745.699871582 W

1 hp(E) = 746 W

1 PS = 735.49875 W

1 bhp = 9810.657 W

1 Btu/h = 0.29307107 W

1 kcal/h = 1.163 W

These kinds of power-unit relationships are standard converter reference values, and horsepower is not a single universal value because different definitions exist [1][2].

Main paired result

The first result row is a convenience output. It uses a simple paired target so the most likely comparison appears first. For example, watts usually pair to kilowatts, kilowatts usually pair to watts, and horsepower types usually pair to kilowatts.

primary converted = P_W / factor to watt(paired target unit)

Mini example

If you enter 1000 for Power value and choose Watt (W) in Convert from, the watt value stays 1000 W.

P_W = 1000 x 1 = 1000 W

kW = 1000 / 1000 = 1

MW = 1000 / 1000000 = 0.001

mechanical hp = 1000 / 745.699871582 = 1.341022...

That is why 1000 W shows as 1 kW and about 1.3410 mechanical horsepower.

Assumptions and limits

This tool assumes exact fixed conversion factors and does not model real machine performance. If a label, motor plate, boiler spec, or HVAC document uses a specific convention, match that exact unit name before comparing values.