App Store Connect is unforgiving about screenshot dimensions: one wrong pixel and the upload bounces. The rules are simple once written down — they're just written down in too many places. Here's the whole map.
The sizes that matter
- iPhone 6.9″ — 1290×2796. The required size for modern iPhones; everything else can be derived from it.
- iPhone 6.5″ — 1242×2688. Still accepted for older devices; Apple scales it where needed.
- iPad 12.9″ — 2048×2732. Required the moment your app supports iPad.
Why uploads get rejected
Nearly every rejection is one of three things: a resized image that drifted a pixel, a stray alpha channel, or a portrait size uploaded into a landscape slot. Export at the exact target resolution — never scale afterward — and all three disappear.