IRAS observations show the existence of a correlation between the infrared luminosity L_IR_ and dust temperature T_d_ in star-forming galaxies, in which larger L_IR_ leads to higher dust temperature. The L_IR_-T_d_ relation is commonly seen as reflecting the increase in dust temperature in galaxies with higher star formation rate (SFR). Even though the correlation shows a significant amount of dispersion, a unique relation has been commonly used to construct spectral energy distributions (SEDs) of galaxies in distant universe studies, such as source number counting or photometric redshift determination. In this work, we introduce a new parameter, namely the size of the star-forming region r_IR_ and lay out the empirical and modelled relation between the global parameters L_IR_, T_d_ and r_IR_ of IR-bright non-AGN galaxies.