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

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  X2 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 X10 Adding 10 the the power in dBm is exactly the same as multiplying the power in Watts by 10