iPhone Duo: the best foldable software yet, on the heaviest iPhone Apple has shipped

Apple announced its first foldable on September 9, seven years after Samsung shipped one. The iPhone Duo costs $1,999, opens from a 5.4-inch cover screen into a 7.6-inch inner display, and reaches stores on October 23. Almost every hands-on landed on the same verdict.

The software is the good part. Reviewers kept pointing at the transitions between the two screens, the reworked one-handed cover-screen layout and the iPad-style split view, rather than at the panel or the hinge. Hardware is where the Duo sits behind the field. At 254 grams and 11.3mm folded it’s heavier and thicker than every book-style Android foldable currently on sale. Any app that skips the iOS 27 update gets letterboxed with black bars. Android’s app-scaling problem is Apple’s app-scaling problem now.

What a foldable actually buys you

Strip the marketing and a foldable is one trade: a small tablet in a phone-sized package, paid for in grams and millimeters. The Duo’s 7.6-inch inner display is the same diagonal as the Galaxy Z Fold 8’s, and both fold down to something Apple’s press release compares to a passport.

The upside is concrete. Two apps side by side without squinting, a book-shaped canvas for the Apple Pencil the Duo supports, and video that fills a screen instead of a strip. Tent and tabletop modes let the thing prop itself up on a tray table, which sounds trivial until hour three of a flight.

Against that sits a bill in four line items: weight, thickness, a crease that’s still there, and a camera system that loses to cheaper phones. The Duo ships with two rear cameras, a 48MP main with a 2x optical crop and a 48MP ultra wide. There’s no dedicated telephoto. Engadget’s reviewer, who otherwise called it Apple’s most exciting device in a decade, said flatly that he wants “a longer, dedicated zoom lens.”

Meanwhile the iPhone 18 Pro Max sits on the same shelf at $1,299 with the full Pro camera stack. That’s a $700 gap for a bigger screen and a worse camera, in a year when component costs are already pushing consumer device prices up. Settle the screen question before anything else on the spec sheet matters.

Where Apple actually did something new

Apple’s answer to the foldable problem is mostly written in software. That’s the part rivals will find hardest to copy. 9to5Google, a site with no reason to flatter Apple, ran a piece on September 10 arguing the Duo is a software story and singling out “the care that went into the transitions between main and internal displays.”

The specifics: a new sidebar on the cover screen that folds the status-bar icons and the dock into one reachable column, a gradual blur that carries state across the hinge as the device opens, and iPadOS-derived split view on the inner panel. 9to5Mac’s Chance Miller called the hinge “impressive” and said the nano-texture matte finish made the crease “hard to notice at most angles.”

Three hardware calls also went right. The Duo is rated IP68 to a maximum depth of six meters for 30 minutes, while Samsung’s Galaxy Z Fold 8 carries IP48, which means no dust seal at all. The under-display FaceTime camera on the inner screen is, per Engadget, “only really visible when you look close.” And Apple dropped Face ID for Touch ID in the side button, a swap Engadget’s reviewer called “the superior solution for quickly unlocking the phone.”

Battery is the quiet win. Apple rates the Duo at up to 31 hours of video playback on the inner display and 44 hours on the cover screen, split across two cells with one in each half. Two batteries is the one place where the extra 11.3mm of folded thickness pays the owner back.

None of that explains why the software feels finished. The software is what people actually noticed, and the likeliest explanation is unglamorous. Apple sat out seven years and eight book-style Galaxy Folds, watched Samsung and Google discover every rough edge in public, then spent the wait writing iOS 27 against a form factor it had already seen fail in other people’s hands.

Where it lands behind Android

Apple’s “thinnest iPhone ever” line is true and misleading at the same time. Open, the Duo is 5.2mm, which beats the 5.6mm iPhone Air. Against the actual competition it loses: the Galaxy Z Fold 8 has been 4.5mm open and 9.7mm folded since July 22, at $1,899.

The weight table is worse:

At 254 grams the Duo is also the heaviest iPhone Apple has ever made, five grams past the 249-gram iPhone 18 Pro Max. For a company that shipped the iPhone Air specifically to prove it could make thin phones, that’s a strange place to land.

Then there’s the app problem. John Ternus, in his first fall keynote as Apple’s CEO, said that “others have created foldables that just feel like two phones awkwardly stuck together,” which is a fair description of early Android hardware and a risky line to deliver when Apple’s own unpatched apps render in portrait with black bars either side. Apple demoed an updated Slack during the keynote. It did not demo what Gmail, Strava or a banking app look like on a 7.6-inch panel nobody told them about.

Apple has historically been better than Google at making developers care about a new form factor, so the gap should close faster here than it did on Android. That’s a prediction about 2027. On October 23 the black bars are real.

Samsung noticed. Samsung Mobile US spent September 9 posting jabs on X, including “So far, so same” and “Let us know when you’re done reheating our leftovers.” The jab has teeth: Samsung’s wide-format Fold 8 redesign landed in July with a 7.6-inch inner panel and a short 5.5-inch cover screen, the exact proportions Apple demoed two months later. That phone is selling well enough that Samsung pulled display driver chips out of its 2027 plan to build more. Motorola piled on the same day with an Instagram teaser showing a blacked-out wide Razr Fold it called “our next move”.

What this means for you

Buy the Duo if you already live inside iMessage, iCloud and Apple Pencil, and if the thing you want most from a phone is more screen. The software genuinely is ahead of what Samsung and Google ship, and the continuity between the two panels is the reason to pay the premium.

Skip it if you shoot a lot of photos at distance. The iPhone 18 Pro Max costs $700 less and keeps the telephoto. Skip it too if 254 grams in a jacket pocket sounds unpleasant, because it is.

Everyone else should wait. Samsung needed eight book-style Folds to reach 201 grams, and a first-generation folding phone is the one that carries every compromise the second one fixes.

One concrete thing to do before pre-orders open on October 16: check whether your five most-used apps have shipped an iOS 27 update. If they haven’t, you’re paying $1,999 for black bars.