App size is how large an app is — both the download size a user fetches from the store and the footprint it occupies once installed. It's an underrated conversion lever: the size shown on the store listing, and the experience of downloading it, directly affect whether a user who tapped "Get" actually completes the install.
Why size costs you installs
- Cellular warnings — large downloads can trigger "download over Wi-Fi" prompts that stall or abandon the install.
- Storage friction — users low on storage hesitate or decline to make room for a big app.
- Download wait — a longer progress bar is more time for the user to lose interest or get interrupted.
- Update drag — large apps are updated less often, slowing the rollout of fixes and new features.
Thresholds and tactics. Apple has historically gated large app downloads over cellular at specific size limits, which is why teams watch the boundary that keeps an app installable without a Wi-Fi prompt. Techniques to control size include app thinning and the [[android-app-bundle]] (delivering only what each device needs), on-demand resources (downloading assets after install), asset compression, and auditing the [[sdk]] stack — since each integrated SDK adds weight. Trimming size is one of the cheaper conversion-rate wins available in ASO.