Abstract: A return-on-investment (ROI) modeling system and method of the present invention calculates a return-on-investment for various scenarios in a semiconductor or data storage fabrication facility (“fab”). The ROI system and method of the present invention calculates the ROI based upon having fab operational details entered. The ROI calculation may be performed for an entire fab or a particular fab processing line. The present invention compares the ROI of a current operation with a contemplated change or set of changes. A complete set of pertinent factors having a relevant or significant impact on an accurate ROI calculation is taken into consideration. Further, the present invention determines costs associated with, for example, the installation of a new tool, downtime costs, short-loop test runs, split-lot testing, design-rule shrinks, and wafer-size changes. If a fab is not currently operating at maximum capacity, an embodiment of the invention calculates an increased capacity capability.