Watt Converter

Created by Luciano Miño
Reviewed by Steven Wooding
Last updated: Jun 28, 2023

Our watt converter is a simple yet useful tool that converts between watts and any power unit. This tool has more than ten different power units for you to choose from, and it's really easy to use.

You can read about the watt conversion calculations in the short text below, where we cover the following:

  • The kilowatt (kW) to watt (W) conversion (and watt to kilowatt conversion);
  • How to convert horsepower to watts;
  • Examples of converting between power units; and
  • More about electric power 💡 and its different units!

To calculate watts in an electrical system given current and voltage, check our watt calculator instead.

What is a watt?

A watt (W) is the International System of Units (SI) unit to measure power. One watt refers to an energy transfer of one joule per second (1 W = 1 J/s = 1 kg × m² / s²).

Therefore, we use watts to describe a system's energy transfer rate.

Like all other SI units, the prefix of power units describes the unit in terms of the watt using powers of ten:



Conversion factor



10−12 W



10−9 W



10−6 W



10−3 W



1 W



103 W



106 W



109 W



1012 W

How to convert watts to kW and mW

How do you convert watts to kilowatts, for example? By using the conversion factor.

If we look at the table in the previous section, we can see that 1 kW = 103 W. Then 1000 is our conversion factor between watts and kilowatts.


  • If you want to convert watts to any other unit from the table, you should take the power in watts and divide it by the conversion factor.
  • If you want to convert any unit from the table to watts, you should multiply by the conversion factor instead.

In the case of milliwatts, the conversion factor would be 0.001.

And that's it! Take the conversion factor from the table and divide or multiply the power by it, depending on if you want to convert from or to watts, respectively.

Other power units

But SI units are not the only units we can use to describe power. We can use others depending on the context, like horsepower (hp) or ergs per second (erg/s).

Our watt converter already works with some of these units. Simply select an option from the dropdown next to any of the variables to change its unit.

Here we will show you how to convert between horsepower and watts easily, but you can read more about these units on our power converter and cgs system of units converter!

How do you convert horsepower to watts?

To convert horsepower (hp) to watts, follow these steps:

  1. Write down the power in horsepower. For example, 160 hp.

  2. Multiple this value by the conversion factor 745.7:

    160 × 745.7 = 119,312

  3. To convert watts to horsepower instead, divide the power in watts by 745.7.


What is 0.5 mW in watts?

To convert 0.5 milliwatts to watts, we can remember that the conversion factor is 1 mW = 0.001 W.

Now since we're converting to watts, we should multiply the value in milliwatts by the conversion factor:

0.5 × 0.001 = 0.0005 W

How many kilowatts are 1200 watts?

Here, the conversion factor is 1 kW = 1000 W. And since we're converting from watts, we should divide by 1000 instead:

1200 / 1000 = 1.2 kW


Are watts and watt-hour the same?

No. A watt is a unit of power corresponding to an energy transfer rate (energy consumed/transferred per unit of time). At the same time, a watt-hour is an energy unit referring to the total amount of energy a system using one watt (1 W) consumes in an hour. 1 W = 1 J/s and 1 Wh = 3600 J

What is 1500 W in kW?

1.5 kW. One kilowatt equals one thousand watts 1 kW = 1000 W, so to convert from kW to W, you should divide the power in watts by 1000: 1500 / 1000 = 1.5.

Luciano Miño
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