Light-gauge Steel Framed (LSF) floor panels are commonly employed in conventional and modular building constructions on the basis of their lightweight nature. Previous research studies on the fire performance of LSF floor panels have been limited to Cold-Formed Steel (CFS) lipped channel and hollow flange joists. Therefore, there is a need for research on the fire performance of the LSF floor panels designed with optimised CFS joists in conventional floor panels and modular floor panels. This paper focuses on the fire performance of LSF conventional and modular floor panels made of optimised CFS joists found in the literature, using Finite Element (FE) analyses. Heat transfer FE models of LSF floor panels were developed and validated against the data available in the literature. Subsequently, the validated FE models were extended to investigate the LSF conventional and modular floor panels made of optimised CFS joists. In total 32 different LSF modular and conventional panels were analysed. A load ratio-critical average joist temperature relationship was derived based on the past test results and extensive FE results. The established relationship in conjunction with time-temperature profiles from the FE analysis was used to predict the Fire Resistance Rating (FRR) of the LSF conventional and modular floor panels made of optimised CFS joists. The results showed that modular floor panels withstand significant standard fire loading compared to the conventional floor panels while optimised CFS joists can also be used to enhance the fire performance.