An optimal design code for centrifugal pumps has been developed to determine the geometric and fluid dynamic variables under appropriate design constraints. The optimization problem has been formulated with a non-linear objective function to minimize one, two or all of the fluid dynamic losses, the net positive suction head required and the product price of a pump stage depending on the weighting factors selected as the design compromise. The optimal solution is obtained by means of the Hooke-Jeeves direct search method. The performance analysis is based on the mean streamline analysis using the present state-of-the-art loss correlations. The optimized efficiency and design variables of centrifugal pumps are presented in this paper as a function of non-dimensional specific speed in the range, 0.5 less than or equal to N-s less than or equal to 1.3. The diagrams presented herein can be used efficiently in the preliminary design phase of centrifugal pumps.