In order to determine the typical work of a finite-size ion on the basis of the electrostatic potential we have to account for the non-vanishing ion extent. We therefore average the electrostatic potential at a given point p over a spherical range Ω of radius r ion . Furthermore, we use weighting factors, w(r), for the averaging which depend on the distance r = p -p from p. Different functions for the weighting factors are considered, all of which belong to a family of shifted and scaled exponential functions: