iPhone Duo has its own screenshot slot in App Store Connect, and it accepts two different display sizes. Here's the manual upload workflow, plus the details that tend to trip people up.
The sizes
From Apple's screenshot specifications:
| Display | Portrait | Landscape |
|---|---|---|
| iPhone Duo outer | 1398 × 2034 | 2034 × 1398 |
| iPhone Duo inner | 2007 × 2853 | 2853 × 2007 |
| iPhone 6.3" (required slot) | 1206 × 2622 (or 1179 × 2556) | swapped |
| iPhone 6.9" (optional) | 1320 × 2868 | swapped |
Files must be PNG or JPEG with no alpha channel, and you can upload up to 10 screenshots per device size. Neither Duo size shares an aspect ratio with a regular iPhone, so scaling your existing set won't give you valid files.
When it becomes mandatory
Apple says Duo screenshots will be required for submissions starting April 2027, for apps built with the iOS 27.1 SDK or later. The SDK condition matters: read it before you plan around the date.
Before you upload
- Start from real captures of your app. Guideline 2.3.3 says screenshots must show the app in use, not just title art or marketing renders.
- On inner-display captures, check that important text and controls stay readable near the fold.
- Make sure the outer and inner sets actually show the two states of your app, rather than the same image cropped twice.
- Flatten everything: no transparency anywhere.
Uploading manually
- In App Store Connect, open Apps, select your app, then an editable iOS version in the sidebar.
- Pick the listing language from the menu at the top right.
- Under Product Page Information, open App Previews and Screenshots, then View All Sizes in Media Manager.
- Choose iPhone, then iPhone Duo, and drop your images in the order you want.
- Upload your 6.3" set (1206 × 2622 portrait) to the required iPhone with Dynamic Island (medium display) slot. If you have 1320 × 2868 files, they go in the optional 6.9" slot. If you skip 6.9", App Store Connect scales screenshots from another size.
- Check order, dimensions and content, save, and repeat for each language.
If Connect rejects a file, it's almost always the slot, the orientation, or an alpha channel. Check those three first.
I build DuoShot, a tool that prepares App Store screenshots including the Duo sizes. We haven't tested uploads to the Duo slot through our own tool yet, so the steps above are the manual path from Apple's documentation, and they work the same whatever tool you use.
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