dBm to Watts converter (dBm to W)
Convert dBm (dBm) to Watts (W) with this free calculator. Type a value, press Convert, and the page applies the same factor shown in the formula below — no rounded shortcut, and nothing is stored on a server.
How to convert dBm to Watts
Convert dBm to watts (W) using the formula P(W) = 10^(dBm/10) ÷ 1000.
P(W) = 10^(dBm/10) ÷ 1000
Use the formula:
Example: Convert 30 dBm to W:
P(W) = 10^(30÷10) ÷ 1000 = 1000 ÷ 1000 = 1 W
What is a dBm?
The dBm (dBm) is the starting or target unit on this page. Use the calculator above to convert values without looking up the factor by hand.
What is a Watts?
The Watts (W) is the starting or target unit on this page. Use the calculator above to convert values without looking up the factor by hand.
This page converts power from dBm into Watts. Use the formula above for the exact relationship between the two units.
dBm to Watts conversion table
Common dBm values and the matching W result, calculated with the same factor as the widget. Highlight a nearby row if you want a quick check without entering a number.
| dBm (dBm) | Watts (W) |
|---|---|
| -30 dBm | 1.000000e-6 W |
| -20 dBm | 1.000000e-5 W |
| -10 dBm | 0.0001 W |
| 0 dBm | 0.001 W |
| 10 dBm | 0.01 W |
| 20 dBm | 0.1 W |
| 30 dBm | 1 W |
| 40 dBm | 10 W |
How this calculator works
The form on this page is a dBm-to-Watts converter. After you enter a number, JavaScript multiplies or rearranges it with the published conversion factor and writes the W result in the output box. The step-by-step panel repeats the arithmetic so you can copy it into homework or a spreadsheet.
Reviewed by Hamsen, founder of GigaTables and a biology engineer. See the about page for how formulas are checked before a tool is published.
FAQ
How many W are in 1 dBm?
Use the formula in the section above. Temperature and logarithmic units are not a single multiply-by-a-constant step.
How do I convert dBm to Watts?
Use the formula:
Is this dBm to W converter free?
Yes. GigaTables calculators are free to use in a browser. You do not need an account, and the values you type are not uploaded.