Apple hasn't shared iPhone Duo hinge tests or given a lifetime fold number like Samsung, but Joanna Stern used a custom device to subject her review unit to more than 32,000 folds over four nights.
Over the course of the testing, Stern said she thought it might be feeling looser as the number of folds increased, but her final conclusion was that she couldn't feel much of a change. A calibrated push-pull gauge used to take readings before and after the Duo fold test showed the hinge was actually stiffer than before.
But in everyday use, I really couldn't feel a difference. So, after 32,000 folds, it felt pretty much the same as day one, which is pretty darn impressive.
Stern didn't comment on whether the fold test caused the crease to be more visible, which can happen over time with other foldable devices. Her testing was done with a case on, and while the machine opened the Duo flat, it didn't close it all the way each time.
Samsung's foldable displays undergo official testing, and in 2025, the display used for the Galaxy Z Fold7 passed a 500,000-fold durability test. Samsung Display says that translates to over 10 years for average users folding their device about 100 times a day, or over six years for users who fold it more than 200 times daily.
Until Apple shares information on display and hinge durability, Stern's test is all we have to go on. It's unlikely to be the last unofficial folding stress test that we see over the next few weeks.
The 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 writeup.
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