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

System Data is the mystery chunk at the bottom of your iPhone Storage screen. Here is what it holds and the safe ways to shrink it.

Updated 23 October 2026 · Works on iOS 18, iOS 26 and iOS 27

What System Data is

System Data (called "Other" in older iOS versions) is everything iOS stores that does not fit into a category: caches, logs, temporary files, downloaded voices and fonts, offline maps and translation files, and streaming buffers. It is normal for it to use several GB, and its size goes up and down on its own.

You can see it in Settings › General › iPhone Storage, at the bottom of the list.

How to reduce System Data

  1. Restart your iPhone. It clears temporary files. Check System Data again after a few minutes.
  2. Update iOS. Settings › General › Software Update. Updates often clean up old caches.
  3. Clear Safari data. Settings › Apps › Safari › Clear History and Website Data.
  4. Clear caches in heavy apps. Social and messaging apps cache a lot. Use the app's own "free up space" or "clear cache" option (TikTok: Settings and privacy › Free up space), or delete and reinstall the app.
  5. Remove streaming downloads. Downloaded shows, songs and podcasts sometimes count partly as System Data.
  6. Trim Messages. Set Settings › Apps › Messages › Keep Messages to 1 year and review large attachments.
  7. Last resort: back up and restore. Back up to iCloud or a computer, then erase and restore your iPhone. This removes stuck System Data but takes time.

The space you can actually control: your photos

You cannot delete System Data directly, and iOS rebuilds some of it. The space you control is your camera roll: duplicates, near-identical shots, screenshots and big videos often add up to far more than System Data.

Clean your camera roll in minutes
CleanPop finds duplicates, similar shots, screenshots and huge videos, lets you swipe to keep or delete, and compresses videos without deleting them. Free to download, with an optional subscription.
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FAQ

Can I delete System Data on iPhone?

Not directly. iOS manages it. Restarting, updating iOS, clearing Safari and app caches, and removing streaming downloads usually shrink it.

Why is System Data so big on my iPhone?

Large caches from apps, logs, downloaded voices and offline files. It often grows after heavy app use and shrinks after a restart or update.

Is it safe to reduce System Data?

Yes, the methods above only clear temporary data. Back up before trying a full erase and restore.