Question
I have some data in MATLAB that represents power density measured in dBW, and I would like to convert the data to units of dBm.
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Expert Answer
Prashant Kumar
PhD Expert
Answered Nov 20, 2025
Assuming that Pxx is measured in Watts, the formula for dBW is
dBW = 10*log10(Pxx/(1 Watt))
= 10*log10(Pxx) for Pxx in Watts
The formula for dBm is
dBm = 10*log10((1000 mW/W)*Pxx /(1 milliWatt))
= 10*log10(1000*Pxx)
= 10*log10(Pxx) + 10*log10(1000)
= 10*log10(Pxx) + 10*(3)
= 10*log10(Pxx) + 30
= dBW + 30
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