dBm ↔ Watt Power Converter
Convert between dBm, mW and W. 0 dBm = 1 mW and 30 dBm = 1 W.
Worked example
30 dBm = 1000 mW = 1 W
Formula
P(mW) = 10^(P(dBm) / 10)
P(dBm) = 10·log₁₀(P(mW))
How it works
dBm is an absolute power level referenced to 1 mW. In EMC testing, signal generator output, amplifier output and receiver input levels are all handled in dBm, so conversions to watts come up constantly. Every +10 dB multiplies power by 10, and every +3 dB roughly doubles it.
Practical tipA "50 W" amplifier is about 47 dBm. Rated power and the 1 dB compression point (P1dB) are different things, so base immunity-test levels on P1dB to avoid a distorted test signal.
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Results and summaries are for reference. For certification and test reports use the latest official standard text and calibrated instrument data. Last updated: 2026-10-10