The actual lethal effect is traditionally determined by calculating the sum of the lethality rates, given in the reference literature. However, to calculate the heat treatment process F-effect for development new sterilization and pasteurization regimes of canned foods, it becomes necessary to vary the parameters of the base temperature and heat resistance characteristic value of the microorganism test culture. To automate the process of computing, the authors developed the software «Heat treatment process lethality calculation» which calculates the lethality rates, the heating lethal effect and the actual lethal effect (F-effect) values of the canned food heat treatment process. In the paper, the software mathematical calculation formula, graphical user interface and functionality are described. The example of pasteurization conditions selection for canned food «Trout in olive oil with the addition of pickled pineapple» in the tin can No. 2, based on the obtained results from the developed software for calculating the actual lethality of the canned food heat treatment processes, is shown.