dBm to Watts Calculator
Convert dBm to watts with P_W = 10^((dBm - 30) / 10). 0 dBm equals 1 mW. Informational, not an RF license or wiring approval.
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How to convert dBm to watts
- Enter dBm and leave watts blank, or enter watts and leave dBm blank.
- The default 0 dBm is 1 milliwatt. Filling both fields shows an error.
- Read watts, milliwatts, and dBm. 10 dB is a factor of 10 in power. 3 dB is about a factor of 2.
- This is a log conversion, not an amplifier design. Nothing is uploaded.
dBm
Decibels relative to 1 milliwatt
| 0 dBm | 1 mW = 0.001 W |
|---|---|
| Formula | P_W = 10^((dBm - 30) / 10) |
| Inverse | dBm = 10 log10(P_W) + 30 |
| Reference | 1 milliwatt into a stated impedance in RF work |
| 10 dB | Times 10 in power |
| Related | Linear watts and amps live on watts to amps |
What dBm is
dBm is a logarithmic power relative to 1 milliwatt. P_W = 10 raised to ((dBm - 30) / 10). At 0 dBm the exponent is -3, so P is 0.001 W, which is 1 mW.
Milliwatt, watt, and the decibel
A milliwatt is 0.001 W. The bel is a log10 ratio. A decibel is one tenth of a bel. dBm fixes the reference at 1 mW. Linear current from watts and volts is watts to amps, a different job.
How this page computes
The page evaluates the power-of-ten formula in this browser. It also lists milliwatts as watts times 1000. It does not assume 50 ohm or 75 ohm unless you bring that context yourself.
Limits
No cable loss, no antenna gain, no EIRP. Informational, not an RF license or wiring approval. CZNull does not receive the dBm value. See the disclaimer.