Ionic conductivity is a foremost transport property that is extensively used to characterize and screen electrolyte systems. Although bulk measurements are done on the macroscopic scale, electrolytic conductivity has its foundation on molecular-scale interactions between solvent and ionic species. Correct interpretations of these molecular interactions and related quantities enable a balanced, comprehensive understanding of conductivity behavior with respect to system conditions (solvent composition, salt concentration and temperature). This work introduces a new methodology that achieves accurate predictions of electrolyte conductivity for a wide range of conditions, based on molecular, physical, and chemical terms. The formalism is universal, making it valid for aqueous and non-aqueous systems alike. The immediate application of the resultant model is candidate electrolytes for lithium-ion and sodium-ion batteries, although many other applications abound for systems that utilize liquid electrolytes. Conductivity predictions are compared to experimental data for a number of electrolytes over a wide range of conditions, demonstrating that exceptional accuracy is attained because the robust model captures multiple salient contributions to conductivity behavior. Model accuracy is well maintained over multi-solvent systems and for extended salt concentrations.