dBm expresses power relative to one milliwatt on a logarithmic scale: 0 dBm is 1 mW, 30 dBm is 1 W, and every 3 dB roughly doubles the power. Wi-Fi routers transmit around 20 dBm (100 mW).
How to use the dBm to Watts Calculator
- Power level
- Every result field is editable: type into Power or any other result and Power level plus every other field update to match.
Results update as you type, and every field accepts the units shown in its menu.
How it works
The dBm value is divided by 10 and used as a power of ten (in milliwatts). Type watts into the result to get dBm.
dBm to power table
| dBm | Power |
|---|---|
| -90 | 1 × 10-9 mW |
| -60 | 1 × 10-6 mW |
| -30 | 0.001 mW |
| -10 | 0.1 mW |
| 0 | 1 mW |
| 3 | 1.9952623 mW |
| 10 | 10 mW |
| 20 | 100 mW |
| 23 | 199.52623 mW |
| 27 | 501.18723 mW |
| 30 | 1 W |
| 33 | 1.9952623 W |
| 37 | 5.0118723 W |
| 40 | 10 W |
| 50 | 100 W |
| 60 | 1,000 W |
What each result means
- Power = 10 ^ (([Power level] – 30) ÷ 10)
- In watts = 10 ^ (([Power level] – 30) ÷ 10)
- In dBW = [Power level] – 30
Formula
P (W) = 10^((dBm − 30) ÷ 10)dBm = 10 × log10(P in mW)Worked example
Inputs — Power level: 20 dBm.
Results — Power = 100 mW; In watts = 0.1 W; In dBW = -10 dBW.
Frequently asked questions
How many watts is 30 dBm?
1 W.
How many mW is 0 dBm?
1 mW.
What does −30 dBm mean?
0.001 mW, one microwatt.
What formula does the dBm to Watts Calculator use?
P (W) = 10^((dBm − 30) ÷ 10).