# What is System Data on iPhone, and how do you reduce it?

**Short answer:** System Data (called "Other" on older iOS) is space iOS uses for caches, logs, temporary files, Siri voices, fonts, dictionaries and the Spotlight index. You can't delete it directly, and no app can. Restart the iPhone, clear Safari's website data, trim Messages and reinstall apps with big caches. iOS also purges caches itself when space runs low. Only erase and restore if it stays huge after all that.

## Steps
1. Open **Settings › General › iPhone Storage** and wait for the bar to finish loading. Scroll to the bottom and note the **System Data** number.
2. **Restart** the iPhone (press and hold a volume button and the side button, then slide to power off). Temporary files are often released at startup.
3. Clear Safari's cache: **Settings › Apps › Safari › Clear History and Website Data**, and choose **All History**. See [how to clear cache on iPhone](/guides/clear-cache-iphone) for other apps.
4. Trim Messages: **Settings › Apps › Messages › Keep Messages › 1 Year**, then review large attachments (see [Messages storage](/guides/messages-taking-up-storage-iphone)).
5. Delete and reinstall streaming and social apps whose storage keeps growing (video, music, social feeds). Their caches sometimes count as System Data.
6. Install pending iOS updates. A downloaded but uninstalled update sits in storage until you install or delete it.
7. Leave the iPhone charging on Wi-Fi overnight and check again: iOS cleans up in the background.
8. Only as a last resort: back up to iCloud or a computer, then **Settings › General › Transfer or Reset iPhone › Erase All Content and Settings**, and restore. This rebuilds System Data from scratch.

## What's inside System Data
| Part | Examples | Can you remove it? |
|---|---|---|
| Caches | Safari website data, streaming buffers, app caches | Partly: clear Safari, reinstall apps |
| Logs and diagnostics | Crash and system logs | No, iOS rotates them |
| System assets | Siri voices, fonts, dictionaries, keyboard data | No |
| Indexes | Spotlight search index, Photos analysis | No, rebuilt by iOS |
| Temporary files | Partial downloads, update files, installers | Yes, mostly by restarting or updating |

Apple's own description of this category: non-removable assets such as Siri voices, fonts and dictionaries, plus logs, caches, the Spotlight index and system data such as the Keychain. iOS deletes cached and temporary files when it needs the space.

## How big should System Data be?
There's no fixed number. Somewhere between **5 and 20 GB** is common, and it rises and falls from day to day. It's a problem when it keeps climbing past 30–50 GB, or when it takes more space than your photos. That usually points to a misbehaving app cache or a stuck update, which the steps above fix.

## Tricks that don't work
- **Changing the date forward.** This "date trick" from forums sometimes makes caches expire. It can also break iCloud sync, Messages and app logins, and the space usually comes back.
- **"System cleaner" apps.** iOS gives every app its own sandbox. No App Store app can reach System Data or other apps' caches, whatever it claims.

## Where Spaceclear fits
Spaceclear can't clear System Data, and nor can any other app. It helps with the space you *can* control: duplicates, similar shots, bursts, screenshots and big videos in your library, plus video compression and Live Photo conversion in [Spaceclear](/). That free space gives iOS room to work, and System Data often settles down once the iPhone isn't nearly full. See also [why your iPhone storage is full for no reason](/guides/iphone-storage-full-for-no-reason).

## FAQ
### Can I delete System Data on iPhone?
Not directly. There's no button for it in iOS, and apps can't touch it. You reduce it indirectly by restarting, clearing Safari data, trimming Messages, reinstalling apps with big caches and installing updates. Erasing and restoring from a backup is the only full reset.

### Why does System Data keep growing on my iPhone?
Usually because an app (streaming, social media, games) keeps caching data, a software update downloaded but didn't install, or iOS is re-indexing after an update. It often drops by itself within a day or two. If it doesn't, reinstall the app whose storage grows the fastest.

### Is it safe to erase my iPhone to clear System Data?
Yes, if you have a complete, recent backup first. Check that **iCloud Backup** finished (Settings › [your name] › iCloud › iCloud Backup) or back up to a computer. Restore takes a while, and you may need to sign back into some apps.

### Does a full iPhone make System Data worse?
Often, yes. With almost no free space, iOS can't finish updates or clear temporary files properly. Freeing a few gigabytes, for example by [emptying Recently Deleted](/guides/empty-recently-deleted-iphone), usually helps.