Recently, the authors have demonstrated load separation in the test records of specimens with semi-elliptical surface cracks. By treating the two-dimensional crack as an equivalent one-dimensional crack, they were able to represent the load in the plastic region as a multiplication of two separable functions: a crack geometry function and a material deformation function. Such a treatment may allow the energy rate interpretation of J formulated for two-dimensional geometries to be utilized in this complex three-dimensional geometry. Moreover, load separation may yield a new single specimen technique for Jpl evaluation. The objective of this paper is to develop and verify this single specimen Jpl form in semi-elliptical surface cracks. A computational finite element model has been developed to generate data for wide ranges of crack length to thickness ratio and crack length to crack width ratio. The computational model has been verified by comparing its numerical results to elastic-plastic experimental test records and also Newman and Raju linear elastic results. The effects of material hardening, specimen thickness, specimen width have been also studied. A single specimen Jpl form has been developed for semi-elliptical surface cracks. Such a form will allow the estimation of J from the load versus crack mouth opening displacement test record of a single specimen.