We propose a method for calculating the ratio R of the indices of the total and the molecular backscattering of the stratosphere from lidar sensing data. The algorithm accounts for aerosol extinction. The algorithm is based on the a priori definition of the lidar ratio profile and does not need large expenditures of computer resources and can be realized a microcomputer. An example of processing of real errors caused by neglecting the experimental data is given. The errors caused by neglecting the aerosol extinction are discussed.