The G-factor, G, corrects for differences in the detection efficiency for fluorescence light of the parallel and perpendicular detector for anisotropy and time-resolved anisotropy experiments.

The G-factor is measured using the integrated (steady-state) fluorescence intensities
Here, the HV and HH represent the parallel and perpendicular detected sample which is horizontally excited.

Alternatively, the G-factor can be determined by matching the tails of the time-resolved fluorescence decays of a fastly rotating/depolarizing dye for VH and VV detection.