In the present paper, a new methodology for the estimation of the single hole mass quantity by a GDI injector is presented and discussed. The GDI injector used for the activity was a five holes nozzle characterized by three holes with the same diameter and two hole with a larger diameter. The different diameters guarantee a significant difference in terms of mass flow. The new methodology described is based on the measurement of the global momentum flow of each single plume and the combination of this measurement with the global mass measurement made with the gravimetric principle. The momentum flux is measured by means of a dedicated test bench that detects the impact force of single spray plume at different distances. The sensing device is moved in different positions and in each point, the force trace averaged on several injection events is acquired. The global mass delivered by the injector is measured collecting a defined number of injections in a becker type vessel and by weigh it. By the combination of these two measurement the estimation of the single hole mass is proposed. The method is validated by means of a dedicated device that is able to collect the mass by single hole and weigh it on a scale. The method is applied in several functional test point of the GDI system and the results point out a good estimation of the single hole mass in all the injection system operating conditions.