Watts to Decibel-Milliwatts conversion

Watts (W) to Decibel-Milliwatts (dBm) conversion calculator and how to convert.

Enter the power in watts and press the Convert button:


How to convert Watts to dBm:

1 W = 30 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


Example:

Convert 20 watts to dBm:

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


Watts to dBm conversion table

Power
(W)
Power
(dBm)
0 W not defined
0+ W -∞ dBm
0.00001 W -20 dBm
0.0001 W-10 dBm
0.001 W0 dBm
0.01 W10 dBm
0.1 W20 dBm
1 W 30 dBm
10 W 40 dBm
100 W50 dBm
1000 W60 dBm
10000 W70 dBm
100000 W80 dBm
1000000 W90 dBm

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