Watts <> dBm <> Volts Converter

This calculator converts between watts, dBm, volts and dBmV.

Select the Impedance then enter any one of the other parameters below and the rest will be calculated automatically

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Impedance (Ω):  50Ω Common in RF and Microwave Systems
75Ω Common in TV and Video Systems
600Ω Common in Audio Systems
Custom Value
 
milli Watts (mW):
Watts (W):
 
dBm:
dBW:
 
VRMS:
VPeak: Assuming a sine wave
VP-P: Assuming a sine wave
 
dBmV: dB relative to 1mV RMS. Often used in the cable TV industry and only valid in 75Ω systems

Most RF engineers will have memorised the following values:

dBm mW Notes
  0   1 Exact by definition of dBm
  3   2 3 dBm is actually 1.995 mW but that’s near enough for most practical purposes
 10  10 Exact
 +3  X 2 Adding 3 to the power in dBm is the same as multiplying the power in Watts by two (actually 1.995 but that’s near enough for most practical purposes)
+10 X 10 Adding 10 the the power in dBm is exactly the same as multiplying the power in Watts by 10