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One of the objectives of utilizing stepped spillways is to increase energy dissipation along spillways and consequently decreasing dimensions of stilling basins. This influences the economical evaluation of the design by reducing costs. The hydraulics of flow over stepped spillways has been investigated by many researchers for the last decade. These investigations have resulted in many hydraulic relationships. Several equations regarding head-loss and friction factor have been developed. Most of these equations are based on an average depth or consider a constant friction factor. In this study, the most effective hydraulic variables have been considered to obtain a general relationship for the friction factor and used in the calculation of water surface profiles along stepped spillways. This relationship has been calibrated by using experimental data and a nonlinear optimization technique. Accuracy of the obtained relations have been evaluated by comparing their results with real ones.