Abstract: Fragment penetration in multilayered target at hypervelocity, is a complex phenomenon and is influenced by fragment and target geometries as well as impact conditions. Authors carried out simulation studies of Tungsten Heavy Alloy (WHA) cubical fragments impacting multilayered spaced target at hypervelocity in various conditions. The target is chosen as a stack of three steel plates, which are separated by 100 mm. The first two plates are 4 mm thick and the third is 10 mm thick. The simulation models are validated by conducting two-stage gas gun trials with 9.5 mm WHA cube against the target. Using these validated models, studies are carried out to estimate the minimum size of a cubical fragment that is required to defeat the target in corner, edge and face orientations; with obliquities of 00, 150, 300 400 and 500; at 3 km/s and 5 km/s. The results are represented by a set of equations and the probability of kill given a hit is estimated for each size of fragment. The methodology is useful to optimize fragment size for neutralization of multilayered spaced targets such as ballistic missiles and spacecraft with a specified probability of kill.