Enter Power
Formula
P(W) = 10(dBm - 30) / 10
dBm is referenced to 1 mW. That means 0 dBm is 1 mW, 30 dBm is 1 W, and every 10 dB increase multiplies power by 10.
Worked Example
For 20 dBm:
P = 10(20 - 30) / 10 = 0.1 W = 100 mW
A 20 dBm transmitter therefore produces one tenth of a watt before cable, connector, and antenna losses.
Use and Limits
EE students use this conversion in communication-system problems. Ham radio and wireless users use it to compare equipment specifications, received signal levels, and link-budget values.
This converts power only. It does not include antenna gain, feed-line loss, impedance mismatch, modulation peaks, or regulatory limits.