Plate heat exchangers (PHEs) play an important role in different technical fields, namely, in energetics, chemical industry, food industry, and others. To use PHE effectively, it is necessary to have correct data for pressure drop. Unfortunately, in open literature, a large difference among different authors occurs. In this work is shown that an essential portion of this difference lies in the choice of the typical length for the calculation of the friction coefficient. Care must be taken to consider the pressure drop of the distribution zone. A three-component model for hydraulic resistance of PHE in turbulent flow regime is proposed in this work. The proposed model shows good agreement with experimental data.