The decibel watt (dBW) is a unit for the measurement of the strength of a signal expressed in decibels relative to one watt. It is used because of its capability to express both very large and very small values of power in a short range of number, eg 1 milliwatt = -30 dBW, 1 watt = 0 dBW, 10 watts = 10 dBW, 100 watts = 20 dBW and 1,000,000 W = 60 dBW.
dBm is referenced to one milliwatt (0.001 W). dBW value in dBm is always 30 more because 1 watt is 1000 milliwatts, and ratio of 1000 (in power) is 30 dB, eg 10 dBm (10mW) is equal to -20 dBW (0.01 W).
Enter one value (either in dBW, dBm or W) and click the "Convert" button next to it to calculate the two other values.