Apple iPhone Duo Fold Tests Deliver Mixed Results as Durability Questions Emerge

Apple’s first foldable smartphone, the iPhone Duo, is attracting significant attention following a series of independent tests examining how its screen and hinge respond to repeated folding. The device represents a major change in Apple’s smartphone design, combining a conventional outer display with a larger internal screen that opens into a tablet-like experience. Although early reviews have praised Apple’s engineering, recent durability experiments have produced mixed results, highlighting the challenges involved in manufacturing a smartphone with a flexible display. Reviewers have subjected the device to thousands of opening and closing cycles to investigate whether the hinge becomes loose, the screen crease becomes more visible or the display suffers damage over time. The findings suggest that the iPhone Duo can withstand considerable mechanical stress, but they also demonstrate that repeated folding may change some physical characteristics of the device. These results are particularly important because consumers purchasing a premium foldable smartphone expect it to remain functional and comfortable to use over several years.

One of the most widely discussed experiments involved technology journalist Joanna Stern, who used a custom-built machine to fold and unfold the iPhone Duo more than 32,000 times over four nights. The test focused on whether repeated movement would noticeably weaken the hinge or affect its operation. According to the findings reported by MacRumors, measurements taken with a calibrated gauge showed that the hinge had actually become stiffer rather than looser after the experiment. Stern said she could not detect a meaningful difference during normal use, suggesting that the hinge remained largely consistent in everyday handling. However, the experiment had limitations: the phone was tested with a case, and the mechanism did not completely close the device during every cycle. Apple has also not published an official folding-cycle rating for the iPhone Duo. Consequently, although the results are encouraging, they should not be interpreted as proof that every device will withstand the same number of folds under all conditions.

The screen crease has produced a different set of results. In testing reported by 9to5Mac, HTX Studio measured the crease depth at approximately 48 microns when the device was new. After 3,000 folding cycles, the measured depth had increased to 167 microns, while the crease’s slope rose from less than 0.1 degrees to approximately 1.24 degrees. These measurements indicate a change in the screen’s physical profile following repeated use, even though the crease may remain difficult to notice during ordinary viewing. The findings are significant because the visibility and feel of the crease are among the most common concerns associated with foldable smartphones. A crease that becomes deeper could affect the user’s experience when scrolling, reading or viewing content against certain backgrounds. However, the test measures a physical change and does not, by itself, establish that the screen is about to fail. More extensive testing across multiple devices will be needed to determine how much variation users should expect over the phone’s lifespan.

Additional testing by German technology publication COMPUTER BILD examined the device over approximately 100,000 folding cycles. The publication reported noticeable signs of wear but no loss of basic functionality at the end of its experiment. Its observations included slight movement in the hinge, minor noises and a reduction in the magnetic force holding the device together. The screen crease also appeared somewhat wider and deeper when the phone was switched off, although the test did not reproduce the display failures reported by some users online. These results offer a more nuanced picture of durability: a foldable phone may continue operating after extensive use even as some mechanical components show signs of wear. Nevertheless, laboratory experiments cannot account for every real-world condition, including accidental drops, pressure on the display, dust entering vulnerable areas, temperature changes and variations in manufacturing. Consumers should therefore distinguish between a device surviving a controlled stress test and a guarantee of long-term reliability under everyday conditions.

Beyond durability, the iPhone Duo faces questions about value, practicality and whether its folding design justifies its premium price. Reviews have praised the near-invisible screen crease during normal use and the usefulness of the larger internal display for reading, watching videos and multitasking. At the same time, reviewers have criticised aspects of the first-generation design, including its weight, limited camera capabilities compared with some conventional Pro models, and reliance on Touch ID instead of Face ID. The starting price of approximately $1,999 also places the device beyond the reach of many smartphone buyers. For Apple, the challenge will be to demonstrate that the benefits of combining a phone and a small tablet outweigh the compromises in cost, portability and hardware design. The latest folding tests do not establish that the iPhone Duo is defective, nor do they prove that its screen and hinge will remain unchanged indefinitely. Instead, they highlight the importance of continued independent testing, transparent durability information and long-term user feedback as foldable phones become more common.