An algorithm to minimize prestressing steel in concrete slabs is presented; it is based on elastic theory and uses the finite element method. The influence-line method and the equivalent-load approach are reviewed and the latter is employed to compute the effects of prestressing. The cable weight of concrete slabs can be minimized by using nonuniform tendon layouts, but this problem requires iteration; since the moments and the prestressing force of a section depend on the tendon layout. A computer program that calculates the effects of different cable groupings and external loadings is developed. Considering certain cable layouts, these individual solutions are then manually superimposed and the sections are checked to determine whether they abide by the allowable stress limits. The best solution, which yields the minimum weight of prestressing reinforcement, is then obtained systematically. The advantage and importance of the algorithm is illustrated by solving three examples.