How it works

dBm expresses an absolute power relative to 1 milliwatt. It is different from dB, which expresses a ratio without specifying an absolute reference. A 10 dB increase multiplies power by ten.

Use P(W) = 10^((dBm − 30) / 10). In the other direction, dBm = 10 log10(P(W) × 1000). For example, 0 dBm is 1 mW, 20 dBm is 100 mW, and 30 dBm is 1 W.

Original archive figures

CLICK TO ENLARGE

The original page linked to externally hosted illustrations. Those files are absent from the backup; the text has been restored without substitute images.

On the bench

Use the calculator below for arbitrary values. These conversions describe power, not voltage; converting to voltage also requires the load impedance and waveform convention.

dBm → watts

1 W

P(W) = 10^((dBm − 30) / 10)

Resources & provenance

Rewritten from the original articles/tut/d3mn6sf_tut007.php page. Component values and historical performance claims have not been independently bench-tested.

Browse all surviving downloads →