The "Storage almost full" message always arrives at the wrong moment: during an important video, before an update, halfway through a holiday. The temptation is to delete whatever comes to hand. It's better to understand where the space really is and to act on what weighs most, while making sure you lose nothing important.
First of all: look at the numbers
Both iPhone and Android have a screen showing how storage is divided: on iPhone under "General", in the storage section; on Android in the storage settings or the file manager app. The screen breaks the space down by category (photos, apps, system, other) and often lists apps by size.
Two numbers to look at for each app:
- app size: the program itself;
- documents and data: what the app has accumulated over time, meaning caches, downloads and saved content.
It's common for a messaging or streaming app to weigh a few hundred megabytes as a program and several gigabytes in data.
Photos and videos: the biggest share
For most people, photos and videos take up the largest share. There are three approaches, which can be combined.
1. Cloud storage with optimisation
iCloud Photos, Google Photos and similar services can keep originals online and leave lighter versions on the phone. When you open a photo, the original is downloaded. Before relying on this feature you must check that the upload is complete: an indicator in the app shows whether items are still waiting.
2. Copying to a computer or external drive
If you'd rather not depend on the cloud, you can periodically copy photos and videos to a computer or a drive and then delete them from the phone. The order is essential: copy first, then check that the files open at the destination, and only then delete.
3. Targeted cleanup
- long videos recorded by mistake or forgotten screen recordings;
- bursts of nearly identical shots;
- accumulated screenshots, often hundreds of them;
- duplicates, which some gallery apps detect automatically.
Remember that deleted photos go to a "Recently Deleted" folder that keeps them for a while: space is only really freed when you empty it.
Messaging apps
Chats accumulate photos, videos, voice notes and documents you've received, often duplicated in the gallery too. The main apps have a storage management tool that shows the heaviest conversations and the largest files, letting you delete them in bulk without deleting text messages.
Two settings stop the problem from coming back:
- turn off automatic download of media, at least for groups;
- turn off automatic saving of received files to the gallery.
App caches and data
A cache is a temporary store that makes apps faster. On Android you can clear it from the app's page in settings without losing accounts and preferences. On iPhone there's no universal command: some apps have an internal option to clear the cache, otherwise the only way is to offload or reinstall the app.
Be careful not to confuse "Clear cache" with "Clear data" or "Clear storage" on Android: the latter resets the app to its initial state, logging you out and losing locally saved data.
Unused apps
A periodic review of installed apps often frees more space than expected. The options:
- uninstall apps you haven't used for months;
- offload the app while keeping its data (on iPhone, "Offload App" keeps documents and data), so you can reinstall it without losing anything;
- turn on automatic removal of unused apps, if the system offers it.
Offline content
Music, podcasts, films, maps and playlists downloaded for offline use take up a lot of room. They were often downloaded for a trip and never removed. Streaming and map apps have a downloads section worth checking now and then.
The "System" or "Other" category
This category includes the operating system, temporary files, downloaded updates and system caches. It can grow considerably and can't be managed directly. It usually shrinks by itself after a restart, after installing a pending update, or when the system needs space. If it stays huge for weeks, a backup followed by a restore is the radical solution.
How much space to keep free
| Free space | Situation |
|---|---|
| over 20% | comfortable, updates install smoothly |
| 10-20% | acceptable, keep an eye on it |
| under 10% | slowdowns and blocked updates |
System updates need temporary space to install: a phone that's always full is often a phone that isn't up to date.
Prevention
- Turn on automatic photo backup and check it once a month.
- Set video quality to a sensible level: high-frame-rate 4K weighs far more than Full HD.
- Every few months, review the heaviest chats and the downloads folder.
In short
- The storage screen shows where the space is: start there, not with random deletions.
- Photos, videos and chat attachments are almost always the largest share.
- Before deleting, copy and check that the files are readable at the destination.
- Clearing a cache is safe; clearing an app's data resets it to its initial state.
- Keeping at least 10-15% free avoids slowdowns and blocked updates.
