The phase modulated full bridge resonant transition converters are widely used for high gain, high power applications. For such applications, the difference in the output voltage predicted from the lossless DC gain model and the actual output voltage is significant. Hence the DC gain loss model for this converters is proposed and analyzed in this paper. The six intervals of operation of the converter are analyzed with non-ideal parameters like winding resistance (RL) of the output filter inductor, on-state resistance (Ron) of MOSFETs, resistance (Rdiode) and forward voltage drop (VD) of output rectifier diodes. The DC gain loss model is derived from the analysis of these intervals. The optimal choice of turns ratio and switching frequency based on the proposed DC gain loss mode is presented. The proposed DC gain loss model is validated in the simulations. The experimental prototype for 250 W is implemented, verifying the model and design presented in this paper. © 2016 IEEE.