Apple’s design team has explained the thinking behind the iPhone Duo, describing how familiar notebooks, the Mac interface, and international A-series paper proportions influenced the company’s first foldable iPhone. In an interview with GQ, Apple CEO John Ternus, Vice President of Industrial Design Molly Anderson, and Vice President of Human Interface Design Steve Lemay also discussed how the device is intended to feel like one phone across its two displays.

Why Apple Looked to Notebooks

Anderson said Apple used the everyday experience of carrying a notebook as a reference point during the Duo’s development. The goal was to create a device that provides more screen space when opened without becoming uncomfortable to carry when closed.

The iPhone Duo’s proportions are based on the international A-series paper system. That approach allows the device to maintain the same proportions in both its opened and closed states, rather than feeling like two unrelated shapes.

Apple also tuned the hinge to control how the phone moves. Its custom variable torque profile is designed to make the device easy to open initially, then increasingly favour staying open and lying flat.

One Interface Across Two Displays

Lemay said the software was designed around the idea that unfolding should feel like expanding the iPhone already in the user’s hand. Apple aimed to preserve the position and recognisability of controls, reducing the need to find familiar buttons again after opening the device.

The transition animation supports that concept by making the inner display appear to grow beneath the outer screen. According to Lemay, Apple wanted the result to feel like a single, cohesive experience rather than two separate products joined together.

The Mac was a major influence on the interface, alongside the iPad and existing iPhone software. Lemay described the result as a collection of the strongest ideas from those products.

Developers Could Shape Future Versions

The interview also addressed how Apple expects the Duo to evolve after launch. Lemay said developers will discover uses that Apple’s design team has not anticipated. Some of those ideas could influence the broader foldable-phone industry and affect the future direction of the iPhone Duo itself.

That leaves room for the device’s software experience to develop beyond Apple’s initial design decisions. The company’s approach combines familiar iPhone controls with concepts drawn from the Mac and iPad, while leaving developers to explore new uses for the larger internal display.

iPhone Duo Release Date and Price

Apple will launch the iPhone Duo on October 23, with pre-orders opening October 16. Pricing starts at $1,999.