Milliwatts to dBm converter (mW to dBm)
Convert Milliwatts (mW) to dBm (dBm) 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 Milliwatts to dBm
Convert milliwatts (mW) to dBm using the formula P(dBm) = 10 × log10(P(mW)).
P(dBm) = 10 × log10(P(mW))
Use the formula:
Example: Convert 100 mW to dBm:
P(dBm) = 10 × log10(100) = 10 × 2 = 20 dBm
What is a Milliwatts?
The Milliwatts (mW) 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 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.
This page converts power from Milliwatts into dBm. Use the formula above for the exact relationship between the two units.
Milliwatts to dBm conversion table
Common mW values and the matching dBm result, calculated with the same factor as the widget. Highlight a nearby row if you want a quick check without entering a number.
| Milliwatts (mW) | dBm (dBm) |
|---|---|
| 0.001 mW | -30 dBm |
| 0.01 mW | -20 dBm |
| 0.1 mW | -10 dBm |
| 1 mW | 0 dBm |
| 2 mW | 3.010299957 dBm |
| 5 mW | 6.989700043 dBm |
| 10 mW | 10 dBm |
| 100 mW | 20 dBm |
| 1000 mW | 30 dBm |
How this calculator works
The form on this page is a Milliwatts-to-dBm converter. After you enter a number, JavaScript multiplies or rearranges it with the published conversion factor and writes the dBm 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 dBm are in 1 mW?
Use the formula in the section above. Temperature and logarithmic units are not a single multiply-by-a-constant step.
How do I convert Milliwatts to dBm?
Use the formula:
Is this mW to dBm 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.