Apple spent years trying to make the crease on its first foldable disappear, and out of the box it mostly worked. The iPhone Duo went on sale today, October 23, and nearly every early review says you have to hunt for the fold line when you look at the screen head-on. The question owners actually care about is what that crease looks like a few months from now.
Chinese tech channel HTX Studio tried to answer that with a folding machine. As UNILAD Tech reports, the channel scanned a brand new iPhone Duo, folded it 3,000 times, then scanned it again. The crease got more than three times deeper. That sounds alarming, and it is worth some context, because every foldable in the test went the same way.
The short version
- HTX Studio measured the iPhone Duo’s crease at 48 microns new, roughly half the thickness of a sheet of paper.
- After 3,000 machine folds it measured 167 microns, and the slope across the fold rose from under 0.1 degrees to about 1.24 degrees.
- Two rival foldables (unnamed, labeled Model A and Model B) also got deeper creases. The Duo ended up level with Model A and behind Model B on depth.
- At 100 folds a day, 3,000 folds is about one month of use.
- Separate tests by Tim Pan (over 11,000 folds) and WSJ’s Joanna Stern (32,000 folds) found the hinge itself held up fine.
What HTX Studio actually measured
HTX Studio is run by He Shijie, one of China’s best known tech YouTubers, and the channel is known for building its own rigs instead of trusting spec sheets. For the Duo, it used a crease-depth scanner that reports the “peak to valley” height, which is the difference between the highest and lowest point across the fold.
Fresh from the box, the iPhone Duo scored 48 microns with a slope under 0.1 degrees (UNILAD cites 0.097). For comparison, a foldable from about five years ago scored 350 microns and was the only phone in the lineup with a clear W-shaped crease you could see without trying. The two current rivals were not named in the video, only labeled Model A and Model B, so we will not guess which Samsung, Google or Chinese foldables they were.
Then all three new phones went into a folding machine for 3,000 cycles and were left closed for a while before the second scan. According to iThinkDifferent’s breakdown of the video, every crease got deeper. The Duo landed at 167 microns, “about the same as Model A and worse than Model B.” On slope it rose to 1.24 degrees, worse than Model B and better than Model A.
Why 3,000 folds is less scary than it sounds
Folding is the whole point of a foldable, so 3,000 cycles is not a torture test. Samsung Display, which makes many of the panels in the industry, assumes about 100 folds a day when it translates its lab numbers into years. Google uses 50 a day for the Pixel Fold line. At 100 a day, HTX’s run equals roughly a month. At 50 a day, about two months.
That matters because creases on foldables do not deepen in a straight line. The flexible layers inside the screen relax under stress early on and then tend to settle. HTX itself made that point with a small piece of advice: leave the Duo open while it charges. Foldables often ship unfolded for exactly this reason, since the materials slowly deform when the phone sits closed.
The honest read is that HTX caught the Duo in the phase where every foldable crease gets worse quickly. What we do not know yet is where it stops. That will take months of real ownership, not a weekend of machine cycles.
The hinge looks solid in every test so far
The crease is a display problem. The hinge is a mechanical one, and on that front the early news is good. HTX found its 3,000-fold Duo still held any angle from 15 to 165 degrees, roughly on par with Model A and better than Model B.
Taiwanese YouTuber Tim Pan went further. He compared a new unit with one folded 500 times by hand, then ran 10,000 machine folds at room temperature and another 1,000 at minus 20 degrees Celsius. Dexerto reports the hinge stayed smooth, the inner screen kept working, and the crease became visibly deeper. He did not publish micron measurements, so his crease verdict is based on what you can see, not a scanner.
The Wall Street Journal’s Joanna Stern built her own rig and put her review unit through more than 32,000 folds over four nights. As MacRumors notes, a calibrated push-pull gauge showed the hinge was actually slightly stiffer afterward. “After 32,000 folds, it felt pretty much the same as day one, which is pretty darn impressive,” she said. Two caveats: the phone was in a case, and her machine did not close it all the way each time. She also did not comment on the crease.
| Test | Folds | Crease result | Hinge result |
|---|---|---|---|
| HTX Studio | 3,000 (machine) | 48 to 167 microns, slope under 0.1° to 1.24° | Holds 15° to 165° |
| Tim Pan | About 11,500, including 1,000 at -20°C | Visibly deeper, not measured | Smooth, opening assist intact |
| Joanna Stern (WSJ) | 32,000+ (in a case) | Not reported | Slightly stiffer on a gauge, same feel |
| Apple | No official rating | “Minimizes crease visibility” | Liquid Metal and titanium hinge |
Apple still has not published a fold rating
This is the part that bugs us most. Samsung says the Galaxy Z Fold 8 hinge is rated for 500,000 folds, and in 2025 the panel used in the Z Fold 7 passed a 500,000-fold durability check verified by Bureau Veritas. Samsung Display translates that into more than 10 years at 100 folds a day. Google says the Pixel 10 Pro Fold will last over 10 years at 50 folds a day. Honor and Oppo publish numbers too.
Apple, which built a hinge with around 100 parts for the Duo (we covered the engineering behind Apple’s first foldable when it launched), has not given any lifetime fold figure for either the hinge or the display. Until it does, YouTube rigs are the only data owners have, and none of them is a controlled lab test.
Apple has quietly planned for a worn crease
There is one more detail that makes the crease story less of a dealbreaker. The Duo’s inner screen uses a nano-texture matte finish that Apple says reduces glare and hides the fold, and HTX found it surprisingly tough. In its pressure test with an Apple Pencil, the Duo showed only a faint mark at about 15 newtons, where another foldable was left with a permanent white spot.
More importantly, that top layer is replaceable. Apple lists the cover layer swap at $49, or $19 with AppleCare+, which we dug into when Apple made the iPhone Duo’s crease layer replaceable. A full inner display repair is a different story at $999 without coverage.
So should crease fears stop you from buying one?
Probably not on their own. Every review so far, from MKBHD’s “first generation fun” verdict to The Verge’s note that you can feel the crease more than you can see it, agrees the Duo starts with the best crease in the business. HTX’s data says that lead shrinks quickly with use and ends up roughly in line with current Android rivals, which is not the same as being bad.
The bigger reasons to wait are elsewhere. Apps still do not make good use of the 7.6-inch inner screen, there is no Face ID, and the 256GB model starts at $1,999. Stock is also the real problem right now, with US delivery estimates slipping into late January 2027. If you are buying, you have time to watch a few more torture tests before your phone even ships. If you want the battery side of the story, our iPhone Duo review roundup breaks down why critics’ numbers were five hours apart.
Sources and further reading
- UNILAD Tech: Man uses machine to fold iPhone Duo 3,000 times
- iThinkDifferent: iPhone Duo crease test after 3,000 folds
- Notebookcheck: iPhone Duo crease put to the test
- Dexerto: YouTuber folds iPhone Duo 10,000 times
- MacRumors: What 32,000 folds did to the iPhone Duo’s hinge
- Bureau Veritas: Samsung Display foldable OLED durability
- Google: Pixel 10 Pro Fold
- Apple: iPhone Duo
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