Purpose: To evaluate one aspect of tipless and helical stone basket function that is critical for ureteral stone extraction: the radial-dilation force. Materials and Methods: Nine commercially available tipless baskets and five commercially available helical stone baskets were tested. Two Teflon blocks were positioned with the lower block sitting on a digital scale and the upper block secured to a plastic frame and base. A 0.01-inch gap was maintained between the blocks using a digital micrometer. Alignment pins secured the position of the lower block in relation to the upper block. A 4-mm cylindrical hole was drilled through the center of the block interface, and each basket was passed through the hole and opened to its fully extended length. The basket was then slowly retracted through the hole, and the maximum force reading was recorded. Twenty repetitions were performed for each basket. Results: Of the tipless baskets ≥3.0F, the Cook N-Circle 3.2F provided the best radial dilation (24.7 ± 0.4 g). For tipless baskets <3.0F, the Sacred Heart Vantage 2.4F provided the best radial dilation (19.6 ± 0.8 g). Of the helical baskets, the Sacred Heart Hercules provided the most radial dilation (102 ± 12.1 g) followed by the Cook N-Force (71.8 ± 4.3 g). Conclusion: The radial-dilation force of tipless and helical stone baskets differs significantly among baskets and may impact stone extraction performance in the ureter.