iPhone Duo screen sizes, resolutions & dimensions

iPhone Duo has two displays. Your app has to work well on both, and it has to handle the jump between them when someone opens or closes the phone.

The two displays

	Outer display	Inner display
Diagonal	5.4″	7.6″
Resolution (as listed by Apple)	1398 × 2034 px	1878 × 2670 px
Pixel density	460 ppi	430 ppi
Refresh	ProMotion, up to 120 Hz	ProMotion, up to 120 Hz
Peak brightness (outdoor)	3000 nits	3000 nits
Finish	—	Nano-texture

Apple says the two panels share the same aspect ratio, so content can scale proportionally when you open the device. The outer display is roughly 90% of the screen area of iPhone 18 Pro.

It opens sideways

The physical dimensions tell the real story:

	Width	Height	Depth
Folded	84.1 mm	117.8 mm	11.3 mm
Unfolded	164.6 mm	117.8 mm	5.2 mm

The height stays the same while the width almost doubles. Held open the natural way, the inner display is a landscape canvas: think of a small paperback lying open, not a tall phone. Apple lists the resolution portrait-first, the way it does for iPad, but the most common way people will use the inner display is wide.

Designing tip: sketch your inner-display layouts as a landscape artboard first. That’s the pose most people will see.

Don’t hard-code any of this

Apple’s guidance is explicit: avoid fixed widths, breakpoints, or any metrics tied to a specific screen. Use size classes instead:

• Outer display: compact width, like a regular iPhone.
• Inner display: regular width and regular height, like a small iPad. The inner display also doesn’t honor your supported interface orientations, so a portrait-locked app will still be shown in landscape.

Safe areas are frequently asymmetric on iPhone Duo, so never assume the left inset equals the right inset. Our simulator checklist covers how to test this.