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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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