hi Andy 1W = 0 dBW = 1000mW = 30 dBm A [dBm] = 10 x log (P) where P is power in milliwatts. P [mW] = 10^(A/10) = (A/10)th power of ten whare A is power in dBm. 3 dBm = 10^0.3 = approx 2 mW 10 dBm = 10^1 = 10 mW de Han JE1BMJ