Abstract: A method for calibrating a linewidth measurement tool and a system for calibrating the linewidth measurement tool each employ a correction of a series of periodic actual measurements of at least one single measurement location of a topographic feature within a linewidth standard with an exponentially weighted moving average of a series of deviations of the series of periodic actual measurements from a corresponding series of regressed data points derived from mathematical regression of the series of periodic actual measurements. Such a correction provides for a more accurate calibration of the linewidth measurement tool and a more accurate measurement of linewidths within microelectronic products while employing the calibrated linewidth measurement tool.