The GORE® CARDIOFORM ASD occluder (ASDO) is approved for closure of ASDs up to 35 mm diameter. With an adaptable central waist, each device size is suitable over a range of defect diameters. Understanding deployed dimensions across various defect sizes will assist operators. Therefore, this study investigates the deployed dimensions of the ASDO as a function of defect size. A 2-mm-thick ASD model with circular defects ranging from 5 to 35 mm was 3D printed. Diameter, width, and left-right disc diameter were measured by fluoroscopy after ASDO devices were deployed in applicable defects. Linear regression evaluated relationships between device size, defect size, and deployed dimensions. Six ASDOs of each size (27, 32, 37, 44, and 48 mm) were deployed in all applicable defects. There was significant ASDO size-defect size interaction in determining deployed ASDO diameter. Diameter was positively associated with defect size for 48-mm (B = 0.13, p < 0.001) and 44-mm (B = 0.11, p < 0.001) ASDOs, while no association was seen for 27-mm, 32-mm, or 37-mm ASDOs. No such interaction existed for deployed width or left-right disc difference. Controlling for ASDO size, width (B = - 0.12, p < 0.001) and left-right disc difference (B = - 0.06, p < 0.001) were negatively associated with defect size. In smaller defects, the 44-mm and 48-mm ASDOs display progressive diameter foreshortening, and all devices display progressive increase in width and left-right disc asymmetry. Anticipating the degree of diameter foreshortening may be critical when attempting closure of fenestrated lesions and/or in patients with limited total atrial septal length.