Particle size distribution is important for the development of both shaped and unshaped refractories. But it is more critical for the castables as they need to satisfy two near contradictory properties, flow and compaction (strength). Continuous particle size distribution of ordered particle sizing systems is employed primarily in advanced castables due to the many advantage such as reducing the water demand, imparting desired rheological characteristics (such as vibratory/thixotropic flow or free flow/self-leveling behavior), minimizing porosity, and maximizing particle contact for enhanced bonding and optimum strength development. Casting and placing properties of castables, which are dependent on flow behavior, are the most critical ones as they affect refractory property development in castables. Many researchers have worked on particle size distribution for castables. Primarily the works of Furnas, Andreasen and Dinger & Funk are well accepted in the castable industries mainly because of their simple approach. This paper reviews these distribution models for castables and their suitability in practical castable development.