In this study, generalized correlations are proposed to predict the effectiveness factors of nickel-based catalyst pellets used in low-pressure steam methane reforming (SMR) systems suitable for small-scale fuel cell applications. Previously, the authors have shown that over 99 % of the total reaction occurs within a thin layer of 0.2 mm thickness from the surface of porous Ni catalyst pellets. Thus, by developing the correlations based on the 0.2-mm-thick active reaction thickness, the proposed effectiveness factor correlations are applicable to catalyst pellets of various shapes used in the low-pressure SMR process. The method of using these effectiveness factor correlations for analyzing fixed-bed SMR systems is also addressed, along with the method for considering the variations in the catalyst properties.