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Watts to dBm conversion

Watts (W) to decibel-milliwatts (dBm), power conversion: calculator and how to convert.

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dBm to watts conversion calculator →

How to convert watts to dBm

The power P(dBm) in dBm is equal to 10 times the base 10 logarithm of 1000 times the power P(W) in watts (W) divided by 1 watt (W):

P(dBm) = 10 · log10( 1000 · P(W) / 1W) = 10 · log10( P(W) / 1W) + 30

so

1W = 30dBm

Example

Convert 20 watts to dBm:

P(dBm) = 10 · log10(1000·20W) = 43.0103dBm

Watt to dBm conversion table

Power (mW) Power (dBm)
0 W not defined
0+ W -∞ dBm
01 W -20 dBm
0.0001 W -10 dBm
0.001 W 0 dBm
0.01 W 10 dBm
0.1 W 20 dBm
1 W 30 dBm
10 W 40 dBm
100 W 50 dBm
1000 W 60 dBm
10000 W 70 dBm
100000 W 80 dBm
1000000 W 90 dBm

dBm to watts conversion →