Where to look
Settings → General → iPhone Storage. The coloured bar at the top splits your used space into categories — apps, photos, media, mail, messages and System Data — and below it every app is listed by size, largest first, with the date you last used it.
That last-used date is more useful than it looks. An app taking three gigabytes that you last opened eight months ago is the easiest decision on the page.
Give it a minute before acting
The chart calculates live, and the numbers move considerably in the first thirty to sixty seconds — System Data especially can read absurdly high and then settle. Acting on the first figure you see is how people end up deleting things they did not need to.
If the totals still look wrong after a couple of minutes, restart the iPhone and look again. A stale calculation after a large update is common.
What each app entry tells you
Tapping an app splits its footprint into two numbers. App Size is the program itself, which offloading removes. Documents & Data is everything it has stored — downloads, caches, saved files — which offloading keeps and deleting removes.
When Documents & Data dwarfs App Size, the app is caching heavily. That is your signal that offloading will not help much and you need to clear its content inside the app itself.
Checking iCloud storage, which is separate
iPhone storage and iCloud storage are different things and run out independently. Settings → your name → iCloud shows the iCloud side, with a breakdown of what is using it — usually Photos and backups.
A full iCloud does not fill your iPhone, and a full iPhone does not fill iCloud. Our iCloud storage guide covers that side.
Checking from a computer
Connecting the iPhone to a Mac and selecting it in Finder shows a storage bar for the device, as does the Apple Devices app on Windows. Hovering over each segment names it.
This is useful when the phone is too full to be responsive, and it is the view to use before an update, since updating from the computer needs less free space on the device anyway.
The recommendations at the top
iOS suggests a few actions above the app list — reviewing large attachments, enabling Optimise Photos, auto-deleting old conversations. These are worth reading because they are calculated from your actual usage rather than being generic.
They are conservative, though. The larger wins are usually further down the list, in the apps you had forgotten were installed. Our storage guide works through them in order of how much they return.
Frequently Asked Questions
Where do I check storage on an iPhone?
Settings → General → iPhone Storage. Wait a minute for the numbers to finish calculating before acting on them.
Why do the storage numbers keep changing?
The chart calculates live and takes 30 to 60 seconds to settle, System Data especially. Restart the iPhone if it still looks wrong.
What is the difference between App Size and Documents & Data?
App Size is the program, which offloading removes. Documents & Data is everything the app has stored, which offloading keeps.
Is iCloud storage the same as iPhone storage?
No. They are separate and run out independently. iCloud is under Settings → your name → iCloud.