Gain (dBi) to Gain (dBd) Converter

About this calculator

Antenna gain can be quoted against two different reference antennas: dBi compares against a theoretical isotropic radiator (equal energy in all directions), while dBd compares against a real-world half-wave dipole, which itself has 2.15 dB of gain over an isotropic source. That fixed offset gives the conversion: dBd = dBi − 2.15 dB (and dBi = dBd + 2.15 dB).

RF and antenna engineers need to convert between the two constantly because manufacturers aren't consistent — WiFi and cellular antenna datasheets often quote dBi, while some amateur radio and broadcast antenna specs use dBd — and comparing two antennas' gain figures without converting them to the same reference can make one antenna look better than it actually is.