In one embodiment, a method for computing current in a digital circuit based on an accurate current model for library cells includes accessing a cell library, for each cell in the cell library corresponding to a cell in a digital circuit, generating multiple waveforms of current drawn by the cell from a power supply according to one or more predetermined values of one or more input parameters of the cell, analyzing the digital circuit to determine one or more actual values of the input parameters of each cell in the digital circuit, for each of the cells in the digital circuit, generating a current waveform according to the determined actual values of the input parameters and a waveform of current drawn by the cell from the power supply generated by the characterization module corresponding to the determined actual values of the input parameters, and summing the current waveforms of the cells in the digital circuit to generate a waveform of current drawn by the digital circuit from the power supply for use in a pattern-dependent methodology (PDM) or a patten-independent methodology (PIM).