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 wave number 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.