Relevance. Sequential pumping is the main method of transportation of large volumes of oil products, which is its main advantage, as there is no need to build separate oil product pipelines. However, this method has one serious disadvantage – the formation of a mixture of petroleum products in the zone of direct contact, which is a difficult to predict process. The volume and length of the mixture must be understood for subsequent actions on their distribution to ensure the required marketable quality of petroleum products, as this will affect their beneficial use, for example, as motor fuels. Aim. To study various domestic and foreign methods and approaches to estimate primary mixture volume, evaluate the advantages and disadvantages of this or that method, verify the accuracy of calculated mixture volumes with real data, derive empirical dependence for real data, compare the calculation results and recommendations for estimation of primary mixture volume. Methods. Mathematical modeling of mixing using different methods, comparative analysis of the obtained data, extrapolation of the function using real data from the Samara–Bryansk technological pipeline. Results. The work analyzes existing approaches and methods for estimating the volume of the resulting mixture of petroleum products, and conducts comparative mathematical modeling. To evaluate the effectiveness of various methods, a comparison was made with the real data from the Samara–Bryansk pipeline. As part of the study, a comparison was made using three models of the mixture formation: without taking into account the primary technological mixture, taking into account the primary technological mixture, taking into account the primary volume of the technological mixture through the method of equivalent lengths.