The hyperfine interactions in octahedral iron compounds are discussed in terms of the effective volumes available for the Fe2+ ion in the lattice, as defined by a touching non‐overlapping muffin‐tin model. The data indicate 〈r−3(t2g)〉 ∞ 〈r〉−3 varying by a factor of 3:1 over the covalency range between FeF2 and FeS. The 3d(eg) orbitals are considerably less expanded than the 3d(t2g) ones, displaying a ratio of 〈r−3(eg)〉 / 〈r−3(t2g)〉 ∼ 2.5 over the same range of covalency. This effect signifies the importance of the asphericity of the boundary conditions in a touching non‐overlapping muffin‐tin model.