The energy efficiency in injection molding is often misunderstood as a function of machine and process technology. However, machine and process serve the purpose to mold a part, thus the required energy to generate a molded component will always predominantly depend on the plastic material and design of the mold cavity to be filled. Therefore, it is stated that the – at theoretical minimum – required energy of a particular part should always be invariant, while the production system and chosen molding parameters determine the efficiency of the production setup and system. The match between a suitable production system and a to be produced part will therefore be critical to reduce energy consumption and increase production efficiency. The analysis of the plasticizing, injection as well as the machine/ mold function processes has been comprehended in a first approach of simple physical models. These allow to describe the theoretically ideal minimum of energy required to produce a component, thus making a specific converting energy predominantly part dependent. A set of dimensionless parameters has been developed to reference actual results derived on various machinery and for different parts relative to the theoretical minimum for each of the above mentioned process aspects. The results show an interesting benchmark for different machine/ part combinations. The theoretical base of the benchmark includes the material processed and the part to be produced, from which processing parameters are derived. The share of energy required during the different process stages (plasticizing, injection, machine/ mold operations) as part of the total energy required, changes subject to the part produced. A comparision for different parts has been experimentally assessed showing quite considerable variations in the suitability of machine/ mold combinations. The efficiency factor allows to benchmark and chose a particular machine/ mold combination for energy consumption.