ERP Calculator

Use this calculator to find the Effective (or Equivalent) Radiated Power (ERP) in dBm, dBW and Watt.


  • Transmit Power (dBm)
  • Antenna gain (dBi)
  • Cable Loss (dB)


ERP = PTx – LC + GAnt – 2.15

where the units of ERP are dBm


Effective Radiated Power is the total power radiated by a half-wave dipole antenna to give the same radiation intensity as the actual source antenna at a distant receiver located in the direction of the antenna’s strongest beam.

Antenna gain in dBi is a measure of its gain compared to an isotropic antenna. Isotropic antennas are hypothetical and radiate signal equally in all directions. An antenna with a higher dBi value has more gain than an antenna with a lower dBi value. Antenna Gain can be calculated from Antenna Factor and Frequency of operation.

Cable Loss LC reduces the output signal level. It is expressed in deciBel or dB. Find Antenna Cable Loss.

The transmitted power from an amplifier for instance is entered in dBm. Convert from Watt to dBm.

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