In this paper, the viability of developing a reduced-order model for determining shock transition zones in converging-diverging nozzles will be presented. The quasi-one-dimensional isentropic pressure equation is coupled with Stodola’s area-Mach number equation, the normal shock relations and the geometric profile data to evaluate the pressure profile inside a nozzle. The proposed work utilizes fundamental fluid relations which only vary with the area ratio, but through the reintroduction of the axial coordinate through profile data, axial gradient information can now be calculated from the model. It is hoped that this reduction in complexity will provide an easy to evaluate criteria that still captures many important features of the flow. In order to fully develop a model, the technique is applied to a planar rectangular nozzle and its efficacy in predicting the experimental pressure profile is assessed.