In this work, density gradient theory (DGT) was combined with electrolyte perturbed-chain (ePC)-SAFT to model the interfacial properties of pure imidazolium-based ionic liquids (ILs). The ePC-SAFT pure-component parameters for the IL-ions were taken from literature for the modelling of density and chemical potential of the pure ILs in the bulk phase. The calculated results were used as inputs for modelling surface tension using DGT. The influence parameters for DGT were obtained from the fitting of the experimental surface tensions. Application of anion-specific influence parameters linearised with the molecular weight of the IL-cation allowed to model surface tensions of pure ILs in a broad temperature range within experimental uncertainty. Surface tensions of ILs which have not been used for the fitting of the influence parameter were predicted in quantitative agreement with experimental data. DGT+ePC-SAFT was further used to predict the interfacial density profile of pure ILs.