The rejection nobody sees coming: alpha channels
Most screenshot uploads that fail are not rejected for their design. They fail on a file detail. App Store Connect refuses any screenshot that contains an alpha channel, and Play Console asks for JPEG or 24-bit PNG “no alpha”. The catch is that a PNG can carry an alpha channel even when every single pixel is fully opaque: the channel is part of the file format, not of the picture.
We measured what a browser does here. A canvas painted edge to edge with a solid colour and saved by Chrome with the default settings comes out as colour type 6 — RGBA, 32 bits per pixel. The image looks identical to an RGB one, and it would still be refused. The same canvas created without an alpha channel is written as colour type 2, plain 24-bit RGB. Many web-based mockup tools use the default.
This tool uses the RGB path, and it does not take that on trust: before a file goes into the ZIP, its header is read back to confirm the exact pixel size and that the colour type is RGB. If a browser still writes an alpha channel, the PNG is re-encoded as 24-bit RGB on the spot. The result panel tells you which of the two happened.
Sizes each store asks for
You do not need every size. Both stores scale down from the largest set you give them, so one set per device family is enough. These are the sizes the tool offers, checked against Apple's screenshot specifications and the Play Console help pages:
| Store | Device | Pixels (portrait) | Needed? |
|---|---|---|---|
| App Store | iPhone 6.9″ | 1320 × 2868, 1290 × 2796, 1260 × 2736 | Yes, one of them |
| App Store | iPhone 6.5″ | 1284 × 2778, 1242 × 2688 | Only without a 6.9″ set |
| App Store | iPhone 6.3″, 6.1″, 5.5″ | 1206 × 2622, 1170 × 2532, 1242 × 2208 | Optional, scaled if missing |
| App Store | iPad 13″ | 2064 × 2752 or 2048 × 2732 | Yes, if the app runs on iPad |
| App Store | iPad 11″ | 1668 × 2420 | Optional |
| Google Play | Phone | 1080 × 1920 or 1440 × 2560 (9:16) | At least 2 screenshots |
| Google Play | Tablet | 1440 × 2560 (9:16) | For tablet listings |
| Google Play | Feature graphic | 1024 × 500 | Yes, for the store listing |
Google Play accepts any size from 320 to 3840 pixels per side as long as the long side is at most twice the short side, but the 9:16 sizes above are the ones that also qualify for its larger promotional formats, which want at least four screenshots of 1080 pixels or more. The App Store allows up to ten screenshots and Google Play up to eight per device type; the tool keeps ten screens at most and reminds you to upload only the first eight to Play.
Your first two screens are an ad in search results
On a phone, an App Store search result shows the icon, the name and the first few screenshots side by side. Each one is roughly a third of the screen wide — about 110 pixels. Most people decide whether to tap from that row alone, without ever opening your page. That makes the first two screenshots the most valuable space you have, and it changes what a good headline is.
- Five words or fewer. At 110 pixels wide, a headline set at the usual size is only about eight pixels tall. Two short lines survive that; a sentence does not.
- The result, not the feature. “Sleep through the night” tells a stranger why to install; “Smart audio engine” does not.
- Contrast that survives shrinking. A pale headline on a busy gradient can look fine at full size and disappear as a thumbnail. Aim for at least 3:1 against the background.
The row of thumbnails under the preview is drawn at that search-result size, and the line above it checks the selected screen: headline height in pixels at that size, word count, and the contrast between the headline colour and the background right beside it. It is a quick way to catch a headline that only works when you zoom in.
How to make a set
-
Take the raw screenshots on a phone (or a simulator) in the order you want them to
appear. File names such as
IMG_1,IMG_2,IMG_10are sorted naturally, so the order survives. - Drop them in. Each becomes a screen with a placeholder headline. Click a thumbnail to select it, write its headline and optional subtitle, and move it earlier or later if the order needs changing.
- Pick a colour theme, then adjust the background, the font and the frame. Style applies to every screen, which keeps the set looking like one piece in the store.
- If the app runs on iPad, add iPad screenshots; they fill the screens in the same order and switch on the 13-inch size.
-
Tick the sizes you need and download the ZIP. Inside, each store and size has its
own folder with files numbered
01,02and so on.
Screenshots taken on an iPhone already match the 6.9-inch shape closely, so they sit in the frame without cropping. A screenshot from a phone with a noticeably different shape, such as an older 16:9 Android phone, is cropped to the frame instead of being stretched — stretching is the one thing reviewers notice immediately.
Why there is no sign-up or export limit
Hosted screenshot builders tend to limit the free tier: five images, two exports a day, a watermark, or a login before the download. Those limits exist because their servers render the images. Here your own browser does the rendering, so a full set for both stores costs nothing to produce and your unreleased app never leaves your machine. The trade-off is that nothing is saved between visits, so export before you close the tab. If you also need the app icon, the app icon generator builds the iOS and Android icon sets the same way, and the Android app icon generator adds the themed-icon layer for Android 13 and later.