One of the challenges in the chemistry of actinide and lanthanide (f-ion) complexes is quantifying exchange coupling of f-ions. While qualitative information about exchange coupling may be readily obtained using the diamagnetic substitution approach, obtaining quantitative information is much more difficult. This article describes how exchange coupling may be quantified using the susceptibility of a magnetically isolated analog, as in the diamagnetic substitution approach, along with the anisotropy of the ground state, as determined by EPA spectroscopy. Several examples are used to illustrate and test this approach.