Critical assessment of perturbation theories for the relative permittivity of dipolar model fluids

•The permittivity of dipolar fluids is a univariate function of the dipole strength.•Perturbation theories from the literature describe the permittivity well.•These findings impact the further development of models for electrolyte solutions. Different perturbation theories for the relative permittivity of dipolar model fluids are assessed by comparison to a comprehensive set of molecular dynamics (MD) simulation data for Stockmayer fluids. With the exception of dense liquids, all MD data are a univariate function of the so-called dipole strength y. Overall, good agreement is found between some of the theories and the MD data.