is inversely proportional to the volume ratio of the central droplet and the hydrated electrolyte and, thus, to their mol fraction ratios (see Appendix for details). D l is the depth of the l th order interaction energy profile. The fitting parameter x l h describes the cross-over from the dilute to concentrated solutions. For x B > x l h the l th order contribution becomes positive indicating unfavorable (endothermic) interaction. We found in our analysis (see Figures below) that solely the dipolar (l = 1) contribution requires in some cases x 1 h < 1. In all fits where quadrupole and octupole contributions become relevant x l>1 h = 1 leads to a satisfying description of the experimental data. Figure shows example fits of individual electrolytes. For CsBr which does not display strong cation-anion interactions, the dipole expansion represents the activity coefficient sufficiently well over the full data range. When increasing the cation-anion interaction strength, such as for the cases of LiCl and ZnCl 2 , complex ion-ion correlations occur in the solution. This increases the importance of higher order contributions to the concentration dependent behavior of the activity coefficient. The quadrupole and octupole terms of our statistical model capture the more complex behavior of LiCl and ZnCl 2 solutions over the whole mole fraction range. The number of contributing multipole components provides a quantification of the impact of (multi-body) ion-ion correlations: complex ion-ion correlations require stronger contributions from an increased number of higher order multipole expansion terms.