Of late, the construction industry seeking a promising substitution for fine aggregates due to the rapid depletion of natural river sand resources coupled with constraints on recycled sand usage. This study demonstrates the development of fly ash-based sand (FAB sand) with fly ash alone as a precursor material by resorting to geopolymerization with cold bonded pelletization technique. The desired sand gradation from 4.75 to 0.075 mm has been achieved by fine-tuning the alkali activator solution (AAS) to binder solids (BS) ratio (0.14, 0.12, 0.10, 0.08), pelletization duration (20, 15, 10 min), and pelletizer speed (15, 10 rpm). For the study purpose, two variety of fly ashes, one with the median particle size (D50) of 25 microns and the other with D50 of 9 microns, are selected. FAB sand is developed with these two fly ashes, and the influence of D50 of precursor material on sand gradation is derived. The analysis of results shows that the fly ash with higher D50 warranted greater AAS/BS ratio (~0.34) and longer pelletization duration (~30 min) while ash with lower D50 consumed lesser AAS/BS ratio (~0.10) with shorter pelletization duration (~15 min) to attain the intended sand size fractions. The results underscore the importance of optimizing mechanical (speed, duration) and chemical (AAS/BS ratio) parameters depending upon the precursor material type. The outcome of the study gives an insight that FAB sand of desirable gradation can be developed by understanding the gradation of precursor material type.