Hydraulic fracturing is one of the most common methods used to study stress-strain state of hydrocarbon reservoir being developed. The process of fracture initiation and propagation is affected by initial stress state in the rock and tensile strength of the rock. Moreover, fracturing fluid filtered through the walls of the well into the well surrounding rock mass also affects the process of fracture propagation. The purpose of this work is to determine the best method for assessing the fracture breakdown pressure according to laboratory experiments. The experiments on hydraulic fracturing were carried out on a special laboratory setup that allows to create loading conditions on a model sample that are close to real conditions at a real field being developed. Some of the known methods based on analysis of the dependencies of borehole pressure on time were used for laboratory data processing.