Free Watt Converter

Power Value

Quick Reference

1 kW = 1,000 W • 1 W = 0.001 kW
1 hp(I) ≈ 745.7 W • 1 W ≈ 0.00134 hp(I)
1 MW = 1,000,000 W • 1 GW = 1,000,000,000 W

1 W = 0.001 kW
1 hp = 745.7 W

Enter a power value and select a unit

Watt Converter — Free Online Power Unit Conversion Calculator

This free online watt converter—a comprehensive power unit conversion calculator—is built to simplify the task of converting between watts and a wide selection of power units. Whether you need to convert watts to kilowatts, find out how many watts a horsepower represents, or quickly perform any electric power conversion, this tool delivers immediate, accurate results. With support for over a dozen units, it serves as a versatile electric power converter for engineers, students, and hobbyists alike.

What is a Watt?

A watt (W) is the SI-derived unit of power, defined as one joule of energy transferred per second:

1\ \text{W} = 1\ \text{J/s} = 1\ \text{kg} \cdot \text{m}^{2} / \text{s}^{3}

In practical terms, power indicates how quickly work is done or energy is consumed. A 100 W light bulb, for example, uses 100 joules of electrical energy each second.

It is important to distinguish power from energy: while power is a rate (W), energy is an amount (joules or watt-hours). One watt-hour (Wh) is the energy delivered when one watt of power flows for one hour, equal to 3600 joules.

Metric Prefixes for Watts

The SI system uses prefixes to express both large and small power values conveniently. The table below shows the most common multiples and submultiples of the watt:

Prefix	Symbol	Value (W)
picowatt	pW	$10^{-12}$
nanowatt	nW	$10^{-9}$
microwatt	µW	$10^{-6}$
milliwatt	mW	$10^{-3}$
watt	W	$1$
kilowatt	kW	$10^{3}$
megawatt	MW	$10^{6}$
gigawatt	GW	$10^{9}$
terawatt	TW	$10^{12}$

How to Convert Watts to Other Units

The core conversion principle is straightforward:

To go from watts to a prefixed unit (e.g., kilowatts), divide the watt value by the factor shown in the table. Because $1\ \text{kW} = 1000\ \text{W}$ , the conversion factor is $10^{3}$ .
To go from a prefixed unit to watts, multiply the prefixed value by the same factor.

For milliwatts the factor is $10^{-3}$ (or 0.001). So, converting 5000 W to kW: $5000 \div 1000 = 5\ \text{kW}$ . Converting 2 mW to W: $2 \times 0.001 = 0.002\ \text{W}$ .

Other Power Units: Horsepower

Beyond the metric prefixes, power is often measured in horsepower (hp), especially in automotive and industrial contexts. This converter includes horsepower as an available unit.

Horsepower to watts: Multiply the hp value by 745.7.
Watts to horsepower: Divide the watt value by 745.7.

For instance, 10 hp equals $10 \times 745.7 = 7457\ \text{W}$ .

Worked Examples

Example 1: Convert 0.5 milliwatts to watts.
Since 1 mW = 0.001 W, multiply the milliwatt value by 0.001:

0.5\ \text{mW} \times 0.001 = 0.0005\ \text{W}

Example 2: Convert 1200 watts to kilowatts.
Because 1 kW = 1000 W, divide the watt value by 1000:

1200\ \text{W} \div 1000 = 1.2\ \text{kW}

Example 3: Convert 160 horsepower to watts.
Multiply the hp by 745.7:

160\ \text{hp} \times 745.7 = 119\,312\ \text{W}

Using the Converter

The interface allows you to pick any input and output unit from dropdown menus. Simply enter the value in the chosen unit, and the tool instantly calculates the equivalent in all other supported units. No manual formulas or conversion factors are needed—the calculator handles everything behind the scenes.

Whether you are working on an electrical engineering project, comparing engine outputs, or studying physics, having a reliable free power unit converter at your fingertips makes unit conversions fast and error‑free.

FAQ

1. How do I convert watts to kilowatts?

Divide the number of watts by 1000. For example, 1500 W ÷ 1000 = 1.5 kW. The same principle applies to other metric prefixes: divide by the factor given in the conversion table.

2. What is the conversion factor between horsepower and watts?

One horsepower (hp) equals approximately 745.7 watts. To convert hp to W, multiply by 745.7. To go from W to hp, divide by 745.7.

3. What distinguishes a watt from a watt-hour?

A watt (W) is a unit of power, measuring the rate of energy transfer. A watt-hour (Wh) is a unit of energy, representing the total energy consumed or supplied by a power of one watt over one hour (3600 joules). They are related but measure different quantities.

4. Which power units does this converter include?

The tool covers metric prefixes from picowatt (10^-12 W) to terawatt (10^12 W), as well as horsepower (hp). This allows conversion between practically any common power unit used in electrical, mechanical, and scientific contexts.

How to Use

Enter a numeric power value in the input field.
Select the power unit you want to convert from.
View the converted values across all power units instantly.