John Ternus and iPhone Duo designers reveal how ordinary paper notebooks were a key inspiration for the new foldable iPhone Duo.
Even as Apple is celebrating the arrival of the iPhone 18 Pro in stores, even its own executives are looking ahead to when the iPhone Duo comes out. CEO John Ternus, hardware executive Molly Anderson and software executive Steve Lemay have been talking to GQ magazine about having started from scratch to build the foldable.
"Steve [Jobs] talked about the intersection of technology and liberal arts," says Ternus, "and I think iPhone Duo is a perfect example of that."
According to Anderson, vice president of industrial design, reaching that goal meant starting with specific aims that were derived from paper notebooks.
"Everyone knows what a notebook feels like in the pocket and what it feels like to carry around," says Anderson. "So that was a big part of the inspiration: 'How do you get to something that gives you space but also feels compact?'"
GQ claims that the iPhone Duo's proportions are actually based on the A-series paper system used internationally. A4 is the international nearest equivalent to US Letter size, for instance.
If the iPhone Duo's proportions were based on that series, they're closest to A5, which is half the size of A4. Even that isn't an exact match, but it's near.
Apple and most people who've tried the iPhone Duo out instead tend to describe it as passport-sized when closed. But of course this is a phone that is meant to be opened out, and Anderson says Apple focused intensely on how it feels to use it open.
Apple's Steve Lemay (left) and Molly Anderson, during the iPhone Duo launch - image credit: Apple.
"We really obsessed about how it feels when you open it — it's incredibly smooth," she says. "The hinge is defined by a custom variable torque profile, so it's easy to open, and then it's actually biased so that it holds itself open and lays flat."
Anderson says the hardware design started, at least in part, with the aim of emulating the convenience of paper notebooks, and making something new. Steve Lemay, vice president of human interface design, says that at the same time, its software grew out of all that had come before.
"You'll see a lot of learnings from iPad in here, learnings from even Macintosh, and learnings from the existing phones," he says. "It's sort of the greatest hits of those products together."
"We didn't want it to feel like you're starting a different operating system when you unfold it," he continued. "And you're never searching for the button you were just looking at."
Pre-orders for the iPhone Duo begin on October 16, 2026. The iPhone 18 Pro is now available both online and also in Apple Stores.