For the same total cost, a public transport route can be served by few large vehicles or more smaller ones. The problem is posed: which out of all equi-cost fleets to select? An algorithm is proposed to guide such selection. To avoid potentially controversial value judgments, the algorithm is based on systematic reduction of the range from which the choice can be made. Considerable reduction in the range of choice can be achieved making use of the “Pareto optimum” principle alone. Analysis is based on a mathematical model describing the relation between the route fleet and characteristics of service to the passenger.