App thinning
Also known as: app slicing, why app smaller on device, App Store download size
App thinning is how the App Store delivers only the parts of an app your specific device needs — the right graphics, code, and resources — so the installed download is smaller than the full app bundle. It happens automatically and is handled by Apple, not by you.
- Delivers only the app variant your device needs
- Automatic — nothing for you to configure
- Why install size can differ from the App Store listing
How app thinning works
A submitted app contains assets for many screen sizes and chip types. App thinning, through app slicing, ships your iPhone or iPad only the variant it can use, so two devices may download noticeably different sizes for the same app.
It also relies on bitcode and on-demand resources, which let parts of an app download later, only when needed. The result is a smaller initial install and less wasted space for content you may never reach.
What it means for your storage
There is no setting to toggle — thinning is automatic. It explains why an app’s “Size” in Settings > General > iPhone Storage can differ from the size listed on the App Store, and why reinstalling on a different device can pull a different amount of data.