Limits
- Apple App Store: up to 10 screenshots per device size and localization, plus up to 3 app previews (videos).
- Google Play: up to 8 screenshots per device type, plus a feature graphic and an optional promo video.
Exact pixel sizes change with new devices; check Apple's and Google's current specifications before you export.
What works
- Lead with the main benefit, not a login or onboarding screen.
- Add short captions. Many users skim captions instead of reading the description.
- Show the app, not abstract art. Users want to see what they'll get.
- Localize captions for big markets.
- Use real user language — phrases from app reviews often make the best captions.
Testing
Screenshots are the easiest thing to test: use product page optimization on iOS or store listing experiments on Google Play and compare conversion rate.
Example
A photo editor replaces its first screenshot (a tool menu) with a before/after image captioned "Fix any photo in one tap". Installs from search rise noticeably within two weeks.