Watt to Decibel-milliwatt Converter
0.5 W is about 26.98970004 dBm. Convert watts (W) to decibel-milliwatts (dBm) below: type a value and the result updates as you type.
W to dBm calculator
Result
Watt to Decibel-milliwatt conversion
1 W = 30 dBmone watt in decibel-milliwatts
1 dBm ≈ 0.001258925412 Wone decibel-milliwatt in watts
Watt (W): SI derived unit: one joule per second.
Decibel-milliwatt (dBm): Power level relative to one milliwatt: 10 times the base-10 logarithm of the power in milliwatts. 0 dBm is 1 mW and 30 dBm is 1 W.
Source:Watt: SI Brochure, 9th edition (BIPM, 2019); Decibel-milliwatt: IEC 60027-3:2002, Logarithmic and related quantities, and their units
How to convert watts to decibel-milliwatts
To convert watts to decibel-milliwatts, divide the amount by 0.001, take the base-10 logarithm, then multiply by 10.
Formula
dBm = 10 × log₁₀(W ÷ 0.001)
Examples
- 0.5 W = 10 × log₁₀(0.5 ÷ 0.001) ≈ 26.98970004 dBm
- 1 W = 10 × log₁₀(1 ÷ 0.001) = 30 dBm
- 100 W = 10 × log₁₀(100 ÷ 0.001) = 50 dBm
Watt to Decibel-milliwatt conversion table
| Watt (W) | Decibel-milliwatt (dBm) |
|---|---|
| 0.001 W | 0 dBm |
| 0.01 W | 10 dBm |
| 0.1 W | 20 dBm |
| 0.5 W | 26.98970004 dBm |
| 1 W | 30 dBm |
| 2 W | 33.01029996 dBm |
| 5 W | 36.98970004 dBm |
| 10 W | 40 dBm |
| 20 W | 43.01029996 dBm |
| 50 W | 46.98970004 dBm |
| 100 W | 50 dBm |
| 1000 W | 60 dBm |
Values rounded to 10 significant digits where needed.
Frequently asked questions
- What is 0.5 W in dBm?
- 0.5 W is about 26.98970004 dBm. To convert watts to decibel-milliwatts, divide the amount by 0.001, take the base-10 logarithm, then multiply by 10.
- How do I convert decibel-milliwatts to watts?
- To convert decibel-milliwatts to watts, divide the level by 10, raise 10 to that power, then multiply by 0.001. The formula is W = 0.001 × 10^(dBm ÷ 10).
- Is this conversion exact?
- Yes. Both units have exact definitions and the factor 0.001 is exact. Displayed results are only rounded when they have many decimal places.