The helical pitch as a function of the molar ratio of chiral dopants was discussed based on the host-host, host-dopant and dopant-dopant flexoelectric interactions in a ferroelectric liquid crystal mixture system. It was found that the wavenumber of the pitch approximately changes from quadratic to cubic dependence on the chiral dopant ratio and that the host-dopant flexoelectric interactions are negligible compared with the host-host and dopant-dopant interactions.