A desk-top method based on kinematic overland flow and Green-and-Ampt infiltration models is developed to determine the time of concentration of and the peak runoff rate from a converging basin. The governing equations of the rainfall-infiltration-overland flow process are written in terms of various dimensionless parameters. Common values of these parameters indicate hydrologic similarity of an infinite number of different converging basins, and therefore the results obtained in terms of these physically-based parameters can be generalized. Using this similarity concept, two charts have been developed to determine the time of concentration of a basin and the peak runoff rate. As illustrated by a sample application, these charts can be used for quick estimates of the design discharge for storm drainage facilities.