What 32,000 bends did to the iPhone Duo hinge

Apple hasn’t shared the iPhone Duo’s hinge tests or given a lifetime bend number like Samsung, but Joanna Stern used a custom device to put her review unit through more than 32,000 bends over four nights.

During testing, Stern said she thought the fabric might become looser as the number of pleats increased, but her final conclusion was that she didn’t feel much change. A calibrated push-pull gauge used to take measurements before and after the Duo bend test showed that the hinge was actually stiffer than before.

But on a daily basis, I really didn’t feel any difference. So after 32,000 folds it feels pretty much the same as the first day, which is really impressive.

Stern didn’t say whether the bend test made the crease more visible, which can happen over time with other foldable devices. Its testing was done with a holster, and while the machine opened the Duo Flat, it didn’t fully close it every time.

Samsung’s foldable screens undergo official testing, and in 2025, the screen used for the Galaxy Z Fold7 passed a 500,000 times durability test. Samsung Display says this translates to more than 10 years for average users who fold their device around 100 times per day, or more than six years for users who fold it more than 200 times per day.

Until Apple shares information about the durability of the screen and hinges, Stern’s test is all we need. This is unlikely to be the last unofficial stress test we see over the next few weeks.

Full details on Stern’s machine, including how it was built, can be found in her YouTube video, and she has more information in her review.