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dBm to Watts Converter

Convert decibel-milliwatts to watt instantly. Formula, worked steps and a full reference table.

How to use it

  • Type the value in decibel-milliwatts — the result updates as you type.
  • Use Swap to flip the direction, or change either dropdown to convert between any two units.
  • Click the result to copy it. The URL updates too, so you can bookmark or share the exact conversion.

Examples

1 dBm0.001258925412 W
5 dBm0.00316227766 W
10 dBm0.01 W
100 dBm10000000 W

One decibel-milliwatts equals 0.0012589254 watts (W). To convert decibel-milliwattses to watts, multiply by 0.0012589254; to go back the other way, multiply by 30 instead.

The converter above does it as you type and shows the working underneath, so you can check the arithmetic rather than take the number on trust.

What decibel-milliwattses and watts actually measure

Decibel-milliwatts (dBm) — dBm is power on a logarithmic scale referenced to one milliwatt, so 0 dBm is exactly 1 mW. Radio, Wi-Fi signal strength and fibre optics.

Watt (W) — The watt is the SI unit of power — one joule per second. Light bulbs, appliances, audio equipment and solar panels.

dBm to Watts conversion table

The most common values, worked out in advance. Anything not listed can be typed straight into the converter.

dBmW
1 dBm0.0012589254 W
2 dBm0.0015848932 W
5 dBm0.0031622777 W
10 dBm0.01 W
25 dBm0.31622777 W
50 dBm100 W
100 dBm10000000 W

How to convert decibel-milliwattses to watts by hand

Multiply the number of decibel-milliwattses by 0.0012589254.

For example, 25 dBm × 0.0012589254 = 0.31622777 W.

Going the other way, divide by 0.0012589254 — or multiply by 30, which is the same thing and easier to do in your head.

Everything runs in your browser

There is no server involved in the calculation. The numbers you type never leave your device, nothing is logged, and the page keeps working with no connection once it has loaded. That is not a marketing line — it is simply how the tool is built, because a calculation like this has no reason to touch a network.

Questions people ask

How many W are in 1 dBm?

This conversion uses a nonlinear formula. For example, 1 dBm = 0.001258925412 W.

Is anything uploaded to a server?

No. The whole calculation happens in your browser. Nothing is sent anywhere, and the page keeps working offline once loaded.

Runs entirely in your browser. Nothing you type is uploaded, logged or shared.

Last updated 18 August 2026