How do you convert milliwatts to watts?

To convert milliwatts (mW) to watts (W), multiply the power in milliwatts by 0.001 (watts = milliwatts × 0.001).

What is 5 milliwatts in watts?

5 milliwatts (5 mW) is equal to 0.005 watts (0.005 W).

Which is larger, 1 milliwatt (mW) or 1 watt (W)?

One watt (W) is larger than one milliwatt (mW). Specifically, 1 W equals 1,000 mW, while 1 mW is 0.001 W.

How do I convert back from watts (W) to milliwatts (mW)?

To reverse the calculation from W to mW, multiply your watt value by the inverse factor 1,000 (or divide by 0.001). You can also click the Swap button in the tool above to flip directions in one click.

How many decimal places should I round mW to W results to?

For everyday comparisons and quick estimates, rounding to 2 decimal places is usually sufficient (for example, 5 mW ≈ 0.01 W). For engineering, laboratory, or machining specifications, select 4 or 6 decimals—or Scientific (10ⁿ) mode—in the calculator toolbar above.

Milliwatts to Watts Converter

Enter the power in milliwatts below to convert it to watts.

Watts to Milliwatts (W → mW)

Convert Milliwatts to Watts

Enter a value in milliwatts (mW) to convert to watts (W).

Value (mW)

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Result

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0.005watts

5 mW = 0.005 W

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Suggested Conversions

Reference:NIST SP 811 (NIST SP 811 App. B.9 (Power & Radiant Flux))

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Milliwatt to Watt Conversion Table

Table showing various milliwatt measurements converted to watts. Click any preset value or arrow to load it into the converter.

Milliwatts (mW)	Watts (W)
1 mW	0.001 W
2 mW	0.002 W
2.5 mW	0.0025 W
5 mW	0.005 W
10 mW	0.01 W
15 mW	0.015 W
20 mW	0.02 W
25 mW	0.025 W
30 mW	0.03 W
50 mW	0.05 W

How to Convert Milliwatts to Watts

To convert milliwatts to watts, multiply the power by the following conversion ratio: 0.001 watts/milliwatt.

Since one milliwatt is equal to 0.001 watts, you can use this simple formula to convert:

watts = milliwatts × 0.001

The power in watts is equal to the power in milliwatts multiplied by 0.001.

For example, here's how to convert 5 milliwatts to watts using the formula above.

watts = (5 mW × 0.001) = 0.005 W

How Many Watts Are in a Milliwatt?

There are 0.001 watts in a milliwatt, which is why we use this value in the formula above.

1 mW = 0.001 W|1 W = 1,000 mW

Our milliwatt to watt calculator automatically converts your power measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.

Milliwatts and watts are both units used to measure power. Keep reading to learn more about each unit.

What Is a Milliwatt?

A milliwatt is a unit of power equal to 1/1,000 of a watt (0.001 W). One-thousandth of a Watt. [1]

The milliwatt is classified as a metric and SI-compatible unit of power. Milliwatts can be abbreviated as mW; for example, 1 milliwatt can be written as 1 mW.

In the metric system, "milli" is the standard SI prefix for thousandths, or 10⁻³. This makes the milliwatt (mW) a convenient decimal multiple of the watt (W).

In practice, milliwatts (mW) are widely used across fine-tolerance laboratory, analytical, and micro-scale power measurements within SI metric workflows, engineering documentation, and technical data sheets.

Learn more about milliwatts in our Power Converter.

What Is a Watt?

Coherent SI unit of power equal to 1 Joule per second (1 J/s). It serves as a primary reference unit for measuring power across scientific and practical applications. [2]

The watt is classified as an International System of Units (SI) unit of power. Watts can be abbreviated as W; for example, 1 watt can be written as 1 W.

As the primary coherent reference unit for power in this category, all other power units are mathematically anchored to the watt (W).

In practice, watts (W) are widely used across standard power applications within International System of Units (SI) workflows, engineering documentation, and technical data sheets.

Learn more about watts in our Power Converter.

When converting power between milliwatts (mW) and watts (W), keep full floating-point precision (1 mW = 0.001 W; 1 W = 1,000 mW) during intermediate calculations and round only the final watt figure to match your instrument tolerance.

More Milliwatt & Watt Conversions

Need to calculate in the opposite direction? Use our watts to milliwatts calculator to switch your starting unit immediately. You can also explore related tools such as converting watts to milliwatts, converting horsepower (hp) to watts, or converting btu/hr to watts.

Convert from Milliwatts

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Frequently Asked Questions

There are 0.001 watts (W) in 1 milliwatt (mW). Conversely, 1 watt (W) is equal to 1,000 milliwatts (mW).

Power Converter

Quick Info

Direct Factor: 1 milliwatt (mW) equals 0.001 watts (W).
Inverse Factor: 1 watt (W) equals 1,000 milliwatts (mW).
Formula: watts = milliwatts ÷ 1000.
Verified Precision: Anchored to official NIST SP 811 and ISO/IEC 80000 standards.

Units Comparison

Milliwatt (mW)

One-thousandth of a Watt.

Watt (W)

Coherent SI unit of power equal to 1 Joule per second (1 J/s).

Kilowatt (kW)

Equal to 1,000 Watts (1 kJ/s).

References

[1]NIST SP 811 · NIST SP 811 App. B.9 (Power & Radiant Flux)
Source
[2]NIST CUU · Derived SI Unit: Watt (W)
Source
[3]BIPM · SI Brochure (9th Ed.) — Power
Source

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References

NIST · BIPM · ISO

[1]
NIST SP 811 (NIST SP 811 App. B.9 (Power & Radiant Flux))·Power Metrology Standard — Milliwatts (mW) to Watts (W)
NIST SP 811 Standard
[2]
NIST CUU (Derived SI Unit: Watt (W))·Unit Specifications: Milliwatt (mW) & Watt (W)
NIST CUU Specification
[3]
BIPM (SI Brochure (9th Ed.) — Power)·Conversion Factors & Mathematical Basis (mW to W)
BIPM Reference

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