Abstract: A method is proposed that makes it possible to calculate the size and coordinates of an emergency gas leak resulting from the depressurization of the gas pipeline based on the data of the measurements of the pressure and flow rate at the outlet from the gas pipeline. The method is based on a mathematical model of a nonisothermal steady flow of a gas mixture through a gas pipeline of constant cross section. The method is a modification of the method for identifying the location of a gas leak in a well. The method makes it possible to accurately calculate the coordinates of the leak in a wide range of changes in the flow rate, pressure, and temperature of the gas at the inlet. In the calculation of the initial approximation, the linear dependence of the coordinate of the gas leak point on the outlet pressure, which is typical for a wide range of problems, is used. This paper provides examples of calculating the coordinates of a leak in gas pipelines using the proposed iterative method and demonstrates its convergence. An example of the effect of the error in setting the outlet pressure on the error in calculating the coordinates of the leak is given. The proposed mathematical apparatus for detecting a gas leak is generalized for detecting a gas leak in wells and ultrahigh pressure offshore gas pipelines.