Friis Transmission Calculator

The Friis transmission equation, as shown below, gives the ratio of received to transmitted power for given antenna gains, ranges, and wavelengths under ideal conditions. The calculator below uses this equation to find any one of the variables, provided all the other variables are known.

friis

Leave the unknown value blank and fill in the remaining values. When one available unit for a value is filled in, the other available units are automatically converted from the entered unit value. Once all but one value is entered in, press Calculate next to the unknown value.

Transmit Power, Pt

Transmit Power, Pt  W 
 dBm
 
 
 
Transmit Antenna Gain, Gt  dBi 
 dBd
 
 
 
Receiver Antenna Gain, Gr  dBi 
 dBd
 
 
 
Received Power, Pr  W 
 dBm
 
 
 
Range,  meters 
 miles
 
 
 
Frequency kHz 
 MHz
 GHz
Wavelength, λ  meters
 cm
 mm