The warning arrives at the worst moment, usually with the camera open. Most advice at that point is to delete photos, which works and is also the most expensive thing you can do, because photos are the part you cannot get back. There is a better order.
Everything here uses the paths Apple documents for current iPhones. Older software nests some of them differently; the section at the end covers that.
First: look at the real breakdown, not the warning
Open Settings, tap General, then tap iPhone Storage. Apple describes this screen in its guide on managing storage on iPhone. It gives a bar across the top and a list of apps underneath, sorted by how much each one holds.
Read the list before touching anything. The usual surprise is that the biggest item is not photos: it is a streaming app holding downloads you forgot, a messaging app keeping years of attachments, or a game with cached levels. Those are recoverable in a way photos are not.
Second: Offload instead of Delete, when the data matters
Tapping an app in that list gives two buttons that sound similar and are not. Offload App removes the app itself and keeps its documents and data; the icon stays on the Home Screen with a cloud symbol, and tapping it reinstalls the app with your data in place. Delete App removes both.
For anything you will use again, Offload is the right one. For an app you installed once and never opened, Delete is cleaner, because Offload keeps data you have no use for.
Apple also has an automatic version. In Settings, tap Apps, tap App Store, then turn on Offload Unused Apps, and the phone removes apps you have not opened in a while when space runs low, keeping their data.
Third: the item called System Data, and why it moves
This is the figure that makes people think something is broken, because it can be several gigabytes and there is no button to clear it. Apple states what it holds: non-removable mobile assets such as Siri voices, fonts, dictionaries, non-removable logs and caches, the Spotlight index, and system data including Keychain and the CloudKit database.
Two things follow from that. The number moving up and down on its own is normal, because caches grow and get trimmed. And there is no supported way to empty it directly: the advice you will find about plugging the phone in and waiting, or restoring from a backup, works by making the system trim its own caches, not by giving you control over them.
Fourth: the things that are genuinely yours to clear
Downloaded video in streaming apps is usually the single largest recoverable item, and each app manages its own downloads inside its settings rather than through iPhone Storage. Message attachments are second, and the Messages entry in the storage list offers to review large ones. Podcasts keep episodes after you have listened to them unless told otherwise.
Photos come last on purpose. If you do delete them, remember the Recently Deleted album holds them for thirty days and that space does not come back until it empties.
If the menu is not where this says
On older software the App Store settings live under Settings, then App Store, rather than under Apps. The iPhone Storage screen itself has been under General for many versions and is the most stable part of this. If your list has no Offload App button at all, the app does not support it, and Delete is the only option.
What this does not solve
A phone that fills up again within a week does not have a storage problem, it has a sync problem: photo libraries set to keep originals on the device, a backup app saving locally, or a messaging app with no attachment limit. Clearing space buys time without changing any of those.
If the answer turns out to be that the phone is simply too small for how you use it, the next question is how long it will keep getting software at all, which decides whether replacing it now is early or overdue. What actually changed in this year's iPhone covers that side of the decision with the manufacturer's own numbers.
Last updated October 4, 2026