A binning process uses curve fitting to create and assign one or more bins based on testing data of operating voltage versus leakage current for test integrated circuits. Each bin is created by assigning an initial operating voltage to the bin and fitting a curve to the testing data population. An equation is generated describing the fitted curve. Integrated circuits are binned by measuring the leakage current at a selected operating voltage and testing the integrated circuit at one or more operating voltages determined based on the fitted curves. The integrated circuits are assigned a maximum operating voltage that corresponds to the lowest tested operating voltage at which the integrated circuit passes the test.