⁹Actual 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 × 10³ greater) than power expressed in dBW.