In order to optimize the end block of a prestressed girder, nonlinear finite element models are frequently used. This way the stresses and possible cracks in the anchorage zones can be predicted in a more reliable manner. However, a preliminary parametric study of nonlinear finite element models has shown that the transfer length has a major influence on the stresses in the concrete and in the reinforcement, and on the crack formation. In this paper this transfer length is examined, firstly by performing a parametric study of the formulations found in literature, secondly by measurements on beams produced at a precast concrete plant. The aim of this parametric study and the experimental research is to get further insight into the transfer length function as required for further numerical analysis of the end zones