This work investigates the error in estimating the strain energy density value through a free coarse mesh model in a finite element analysis. Several numerical simulations were carried out to acquire this value both according to the conventional methodology of the strain energy density method and according to the procedure shown in the present work that can be applied directly in the post‐processing phase of the simulation without requirements for the model. The main advantage of this new procedure is the possibility to apply the method also to those numerical simulations already done for other purposes decreasing considerably the effort of the researcher and the calculation time. The numerical simulations carried out show that the strain energy density value can be estimated with an error of 1% also with a free coarse mesh model having a mesh size near the notch tip of 1/8 of the control volume radius.