This paper aims to present a methodology for the calculation of technical losses per segment of a power distribution system. One of the most important data is the billed energy of each customer. After this calculation, it is achieved the energy supplied by each feeder. This calculated energy is, then, compared with the measured energy. As a result of this comparison, it is possible to correct the technical losses calculated previously, considering the flow of the non-billed energy (theft and fraud) through the network. Consequently, it is achieved a new value for the technical losses and for the non-technical losses. On this paper it is presented the methodology for the calculation of technical losses with the correction through the measurements and the results obtained.