We introduce a corrective function to compensate errors in contact area computations coming from mesh discretization. The correction is based on geometrical arguments, and apart from the contact area itself requires only one additional quantity to be computed: the length of contact/non-contact interfaces. The new technique enables to evaluate accurately the true contact area using a very coarse mesh, for which the shortest wavelength in the surface spectrum reaches the grid size. The validity of the approach is demonstrated for surfaces with different fractal dimensions and different spectral content using a properly designed mesh convergence test. In addition, we use a topology preserving smoothing technique to adjust the morphology of contact clusters obtained with a coarse grid. © 2017 Elsevier Ltd