Add dBm Calculator

dBm stands for decibels (dB) relative to one milliwatt. It is an absolute unit of power.

How you add two dBm values together to find the total power?

This tool performs the addition of two dBm power values.

Power1 + Power2

Simply enter Power1 and Power2 with the appropriate units. It computes the sum in dBm or dBW.


Note that since dBm is a logarithmic value you cannot add two dBm values directly.

Instead you have to:

  • Convert dBm to Watt
  • Add Watt values
  • Convert the result back to dBm

Example calculation

The sum of power levels 30 dBm and 3 dBm is 30.01 dBm (not 33 dBm).

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