Milliwatts to Watts (mW to W) Converter

In electronics and communication systems, power is often expressed in milliwatts for precision. However, when scaling up or comparing with larger devices, it’s useful to convert milliwatts back into watts.

This article will guide you step by step through converting milliwatts to watts, with clear formulas, tables, and practical examples.

Definitions of Milliwatt and Watt

Let’s get started by understanding the key definitions of Milliwatt (mW) and Watt (W). Understanding these terms will allow you to perform conversions confidently.

What is a Milliwatt (mW)?

A milliwatt (mW) is a unit of power in the SI system equal to one thousandth (1/1,000) of a watt (0.001 W).

Definition and Scale of Milliwatt (mW) — Definition and scale of a milliwatt (mW)

Milliwatts are commonly used to measure small power levels in electronics and communication systems. Devices such as laser pointers, wireless transmitters, hearing aids, and portable audio equipment often operate in the milliwatt range, making this unit ideal for expressing precise, low-power outputs.

What is Watt?

Watt (W) is the SI derived unit of power, named after James Watt, the Scottish engineer who improved the steam engine. It measures the rate of energy transfer per unit time.^[1]

Mathematically, one watt equal to one joule per second (1 J/s). 1 W = 1 j/s

$$\boxed{1 \,\text{Watt} = 1 \,\frac{\text{Joule}}{\text{Second}}}$$

Where:

j = joule unit of energy
s = second unit of time

According to SI prefixes^[2], which are based on powers of 10, a watt (1 W) is equivalent to one thousand milliwatts (10³ mW or 1,000 mW).

Watts to Milliwatts Conversion Scale — Watts to milliwatts conversion scale

It is widely used to quantify electrical, mechanical, and thermal power in everyday applications such as light bulbs, appliances, and motors.

mW to W formula

Let’s take a closer look at the conversion formula so you can carry out these conversions independently, whether using a calculator or doing it manually with pencil and paper.

SI Prefixes and Values — SI multiples and submultiples

The milli- prefix in the International System of Units (SI) represents a multiplier of 10^-3 (0.001). So, to convert from milliwatts to watts, divide the number of milliwatts (P_(mW)) by 1,000.

P_(W) = P_(mW) ÷ 1,000

\text{P}_\text{(W)} = \frac{\text{P}_\text{(mW)}}{1{,}000}

Or remember the mW-to-W conversion factor: 1 mW = 0.001 W

mW to W conversion table

The conversion table below provides a handy reference for converting power measurement units from milliwatts (mW) to watts (W). It covers commonly available power values, allowing for easy and quick conversions between these units of measurement.

Milliwatts (mW)	Watts (W)
1 mW	0.001 W
100 mW	0.1 W
500 mW	0.5 W
1,000 mW	1 W
2,000 mW	2 W
4,000 mW	4 W
5,000 mW	5 W
10,000 mW	10 W
20,000 mW	20 W
30,000 mW	30 W
40,000 mW	40 W
50,000 mW	50 W
60,000 mW	60 W
70,000 mW	70 W
80,000 mW	80 W
90,000 mW	90 W
100,000 mW	100 W
200,000 mW	200 W
500,000 mW	500 W
800,000 mW	800 W
1,000,000 mW	1,000 W

Milliwatts (mW) to watts (W) conversion table

Examples

Now, let's look at an example that illustrates the calculations required to convert from watts to milliwatts (W to mW).

Example: Wireless Transmitter

Suppose you’re testing a Bluetooth transmitter, and the datasheet specifies an output of 5,000 mW. However, your documentation requires power values in watts (W).

Solution

Since 1 W = 1,000 mW, we can convert 5,000 mW to watts by using the following formula:

$$\text{P}_\text{(W)} = \frac{\text{P}_\text{(mW)}}{1{,}000}$$

$$\text{P}_\text{(W)} = \frac{5{,}000}{1{,}000} = \boxed{5 \,\text{W}}$$

Therefore, the transmitter outputs 5 W of power.

To solve the problem with our calculator, follow the steps below:

Enter the value in milliwatts: For this example, enter 5,000 into the From box.
View the result: The converter instantly calculates and displays the equivalent value in watts: 5 W.

Milliwatts to Watts (mW to W) conversion example — Steps to convert from milliwatts to watts with our calculator

FAQs

Is 1 milliwatt or 1 watt larger?

A watt (W) is a thousand times larger than a milliwatt (mW). Here are the relationships between the units:

1 W = 10³ = 1,000 mW
1 mW = 10^-3 = 1 ÷ 1,000 = 0.001 W

How to convert from milliwatts to watts?

To convert power from milliwatts (mW) to watts (W), follow these simple steps:

Write down the power value in milliwatts (mW).
Divide it by 1,000.
The result is the power in watts (W).

Why do I need to convert milliwatts to watts?

Converting milliwatts to watts is essential when scaling small device outputs to larger systems. For example, a wireless transmitter rated at 2,000 mW is easier to compare as 2 W when evaluating against household electronics or energy consumption.

You now know how to convert power units from milliwatts (mW) to watts (W). You can quickly use our calculator to convert between the power measurement units to save time for future calculations.