How to convert milliwatts to dBW
dBW = 10 × log₁₀(mW × 0.001)Express the quantity as a ratio to the reference level, take the base-10 logarithm, then multiply by 10.
Worked examples
- 1 milliwatt1 mW → −30 dBW
- 5 milliwatts5 mW → −23.01029996 dBW
- 10 milliwatts10 mW → −20 dBW
- 20 milliwatts20 mW → −16.98970004 dBW
- 100 milliwatts100 mW → −10 dBW
Milliwatts to dBW conversion table
Values are calculated by the conversion engine using the full formula and rounded to 8 significant figures.
| Milliwatts (mW) | DBW (dBW) |
|---|---|
| 0.1 mW | −40 dBW |
| 0.25 mW | −36.0206 dBW |
| 0.5 mW | −33.0103 dBW |
| 1 mW | −30 dBW |
| 2 mW | −26.9897 dBW |
| 3 mW | −25.228787 dBW |
| 4 mW | −23.9794 dBW |
| 5 mW | −23.0103 dBW |
| 6 mW | −22.218487 dBW |
| 7 mW | −21.54902 dBW |
| 8 mW | −20.9691 dBW |
| 9 mW | −20.457575 dBW |
| 10 mW | −20 dBW |
| Milliwatts (mW) | DBW (dBW) |
|---|---|
| 12 mW | −19.208188 dBW |
| 15 mW | −18.239087 dBW |
| 20 mW | −16.9897 dBW |
| 25 mW | −16.0206 dBW |
| 30 mW | −15.228787 dBW |
| 40 mW | −13.9794 dBW |
| 50 mW | −13.0103 dBW |
| 75 mW | −11.249387 dBW |
| 100 mW | −10 dBW |
| 250 mW | −6.0205999 dBW |
| 500 mW | −3.0103 dBW |
| 1,000 mW | 0 dBW |
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-watt (dBW)
Power level relative to 1 W: dBW = dBm − 30. It is a logarithmic level: 0 dBW corresponds to 1 W.
Frequently asked questions
What is the formula to convert milliwatts to dBW?
dBW = 10 × log₁₀(mW × 0.001). Express the quantity as a ratio to the reference level, take the base-10 logarithm, then multiply by 10.
What is 5 milliwatts in dBW?
5 mW = −23.01029996 dBW.
Is this mW to dBW 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.