A physical measuring tool comprising one or more members for determining the correct length of stock of various shapes of a given thickness and width range required to form various enclosed shapes with predetermined internal dimensions. One embodiment is an easy to use enclosed shape measuring tool that allows jewelers to fabricate rings of various widths from stock with great precision and fit without costly revision, as the measurements it makes are calibrated to the proportional relation among the thickness, length, width of material, and finished fit of ring. Each measuring element includes a raised fence for bracing material against to maximize measurement accuracy, and other convenient elements such as a thickness-measuring member. Such a tool replaces mathematical calculations and charts for determining the ratio among length and thickness of stock, and width and interior dimensions of enclosed shapes representing a significant time and resource saver for fabricators.