^{9}Actual signal power is typically expressed as a decibel ratio to a reference power of either 1 milliwatt (dBm) or 1 watt
(dBW). Thus, 250 mW of RF power may be expressed as 10 log 250
1 = 23.98 dBm or as 10 log 0.25
1 = −6.02
dBW. Power expressed in unit of dBm will always be 30 dB greater (1 × 10^{3} greater) than power expressed in
dBW.