dBm is an abbreviation for the dB referenced to one milliwatt.
Note 1: dBm is used in communication work as a measure of absolute power values. Zero dBm equals one milliwatt. A 3 dBm increase represents roughly doubling the power, which means that 3 dBm equals 2 milliwatt. For a 3 dBm decrease the power is reduced by one half, making -3 dBm equal to 0.5 milliwatt.
Note 2: In DOD practice, unweighted measurement is normally understood, applicable to a certain bandwidth, which must be stated or implied.
Note 3: In European practice, psophometric weighting may be implied, as indicated by context; equivalent to dBm0p , which is preferred.
1 See also
Zero dBm transmission level point
2 Source
Units of measure
