iPhone Duo specs for developers: displays, size classes, poses and tools
Updated · 4 min read · Markdown version
iPhone Duo has a 5.4-inch outer display at 1398 by 2034 pixels and a 7.6-inch inner display at 1878 by 2670 pixels and 430 ppi; both share one aspect ratio, the outer display reports compact width and the inner display reports regular width and regular height.
A reference sheet of the numbers and system behaviors an iOS developer needs when targeting iPhone Duo. All figures are from Apple's announcement and developer materials published September 9, 2026.
Displays
| Outer display | Inner display | |
|---|---|---|
| Diagonal | 5.4 inches | 7.6 inches |
| Resolution | 1398 x 2034 px | 1878 x 2670 px |
| Pixel density | 460 ppi | 430 ppi |
| Refresh rate | 120 Hz ProMotion | 120 Hz ProMotion |
| Peak brightness | 3000 nits | 3000 nits |
| Aspect ratio | About 1.46:1 (2034/1398) | About 1.42:1 (2670/1878); Apple describes both as roughly 1.4:1 so layouts carry across |
| Finish | Glass | Matte nano-texture, reduces crease visibility |
Size classes by pose
| Pose | Horizontal size class | Vertical size class | Behaves like |
|---|---|---|---|
| Closed, portrait | Compact | Regular | A standard iPhone |
| Closed, landscape | Compact | Compact | A standard iPhone in landscape |
| Open, portrait | Regular | Regular | A small iPad |
| Open, landscape | Regular | Regular | A small iPad in landscape |
| Half folded, portrait | Regular | Regular | Two halves; content should avoid the fold |
| Half folded, landscape | Regular | Regular | Top and bottom halves; ideal for video and camera |
Window states on top of the poses
| Window state | Horizontal size class | Vertical size class | Behaves like |
|---|---|---|---|
| Open, side by side with another app | Compact | Regular | iPad Split View |
Rotation is not a pose of its own; it is an orientation applied to each fold state. Apple's guidance is to make layout decisions from size classes, never from orientation, because the inner display does not honor supported interface orientations the way a single-screen iPhone does.
Reserved regions
iOS 27.1 introduces ReservedRegion in SwiftUI and UIViewReservedRegion in UIKit. Apps query regions by kind. The division kind is the fold; the occlusion kind is the camera. Standard system controls avoid both automatically; custom UI must opt in.
Tooling
- Xcode 27.1 with the iPhone Duo simulator in Device Hub. Controls open, close, rotate and fold the device.
- iOS 27 SDK: content extends left of the status bar on the inner display.
- iOS 27.1 SDK: content reaches the screen edge; navigation and toolbar buttons lay out vertically; ReservedRegion API available.
- Concentricity APIs for corner shapes that match the display.
Commercial facts
| Fact | Value |
|---|---|
| Announced | September 9, 2026 |
| Ships | October 23, 2026 |
| Starting price | $1,999 (256 GB) |
| Top configuration | $3,199 (2 TB) |
| Launch partner apps | Netflix, Zoom, Slack among the first adapted third-party apps |