The paper investigates the peel test of an elastic-plastic film on an elastic substrate. The case of a film material presenting a saturation of the yield stress is considered. Based on earlier approaches of the literature , see for instance Kim and Aravas (1988) (Kim, K.S., Aravas, N., 1988, International Journal of Solids and Structures, 24, 417-435), a semi-analytical expression for the work done by bending plasticity is proposed. The validity of the present expression is established based on finite element calculations. It is shown that for the interpretation of the results of peel test at 90 degrees when the peel force and the curvature are measured , the present approach can provide a precise value of the interface fracture energy.