How to convert milliwatts to dBm
dBm = 10 × log₁₀(mW)Express the quantity as a ratio to the reference level, take the base-10 logarithm, then multiply by 10.
Worked examples
- 1 milliwatt1 mW → 0 dBm
- 5 milliwatts5 mW → 6.989700043 dBm
- 10 milliwatts10 mW → 10 dBm
- 20 milliwatts20 mW → 13.01029996 dBm
- 100 milliwatts100 mW → 20 dBm
Milliwatts to dBm conversion table
Values are calculated by the conversion engine using the full formula and rounded to 8 significant figures.
| Milliwatts (mW) | DBm (dBm) |
|---|---|
| 0.1 mW | −10 dBm |
| 0.25 mW | −6.0205999 dBm |
| 0.5 mW | −3.0103 dBm |
| 1 mW | 0 dBm |
| 2 mW | 3.0103 dBm |
| 3 mW | 4.7712125 dBm |
| 4 mW | 6.0205999 dBm |
| 5 mW | 6.9897 dBm |
| 6 mW | 7.7815125 dBm |
| 7 mW | 8.4509804 dBm |
| 8 mW | 9.0308999 dBm |
| 9 mW | 9.5424251 dBm |
| 10 mW | 10 dBm |
| Milliwatts (mW) | DBm (dBm) |
|---|---|
| 12 mW | 10.791812 dBm |
| 15 mW | 11.760913 dBm |
| 20 mW | 13.0103 dBm |
| 25 mW | 13.9794 dBm |
| 30 mW | 14.771213 dBm |
| 40 mW | 16.0206 dBm |
| 50 mW | 16.9897 dBm |
| 75 mW | 18.750613 dBm |
| 100 mW | 20 dBm |
| 250 mW | 23.9794 dBm |
| 500 mW | 26.9897 dBm |
| 1,000 mW | 30 dBm |
About the units
Milliwatt (mW)
The milliwatt (mW) is a unit of power level (dbm, dbw) in the International System of Units (SI). One milliwatt equals 0.001 watts (W).
Decibel-milliwatt (dBm)
Power level relative to 1 mW: 0 dBm = 1 mW, 30 dBm = 1 W, −30 dBm = 1 µW. It is a logarithmic level: 0 dBm corresponds to 0.001 W.
Frequently asked questions
What is the formula to convert milliwatts to dBm?
dBm = 10 × log₁₀(mW). Express the quantity as a ratio to the reference level, take the base-10 logarithm, then multiply by 10.
What is 5 milliwatts in dBm?
5 mW = 6.989700043 dBm.
Is this mW to dBm converter accurate?
Yes. Both units are defined exactly in terms of SI units, so the conversion factor is exact; results are shown to 12 significant figures by default and you can change precision in the converter. Calculations run in your browser using the same tested engine that generated this page.