If you've ever checked your iPhone's storage and noticed "System Data" (previously called "Other") taking up a large chunk of space, you're not alone. This guide explains what it is, why it grows, and what you can do about it.
Table of Contents
- What Is System Data?
- How to Check System Data Usage
- How to Reduce System Data
- If It Still Won't Shrink
- Summary
What Is System Data?
What's Included in System Data
"System Data" is a catch-all category that includes various types of cached and temporary files that iOS doesn't attribute to specific apps. This includes:
- Safari and app caches
- Mail attachment previews and downloaded data
- Streaming media caches (music, video, podcasts)
- iMessage attachment caches
- iOS system logs and update files
- Siri voice data and font caches
Why It Keeps Growing
System Data tends to grow over time because iOS continuously generates caches and logs during normal use. Streaming content, browsing the web, and exchanging messages all contribute. iOS is supposed to clean up automatically when storage gets tight, but this doesn't always work perfectly — which is why it can balloon to 10 GB or more.
How to Check System Data Usage
Go to "Settings" → "General" → "iPhone Storage." Scroll to the bottom of the storage bar graph to see "System Data" (or "Other" on older iOS versions). Tap it for more details. Note that the number may fluctuate — it's worth checking a few times over several days to get an accurate picture.
How to Reduce System Data
Restart Your iPhone
A simple restart clears temporary caches and logs from memory. This alone can reduce System Data by a noticeable amount, especially if you haven't restarted in a while.
Clear Safari Cache
Safari's website data is one of the biggest contributors to System Data. Go to "Settings" → "Safari" → "Clear History and Website Data." This removes cached pages, cookies, and browsing history. You'll be signed out of websites, so keep that in mind.
Clear App Cache
Some apps (like social media and news apps) build up large caches over time. Check individual apps in "Settings" → "General" → "iPhone Storage" for any that show large "Documents & Data" sizes. Some apps offer a "Clear Cache" option in their settings; for others, deleting and reinstalling the app is the most effective way to clear the cache.
Set iMessage Retention Period
By default, iMessage keeps all messages forever. Accumulated attachments — photos, videos, GIFs — can take up a surprising amount of space, much of which ends up in System Data. Go to "Settings" → "Messages" → "Keep Messages" and change it to "1 Year" or "30 Days" to automatically remove older messages.
Clear Streaming App Cache
Music and video streaming apps like Spotify, Apple Music, YouTube, and Netflix store cached data for smoother playback. Check each app's settings for an option to clear the cache, or delete and reinstall the app to start fresh.
If It Still Won't Shrink
Update iOS
iOS updates sometimes resolve storage-related bugs and improve how the system manages cached data. If you're running an older version, updating may help reduce System Data. Go to "Settings" → "General" → "Software Update."
Back Up and Reset Your iPhone
If System Data remains stubbornly large after trying everything above, backing up your iPhone and performing a factory reset is the most reliable fix. This will erase all data on your device, so make sure you have a complete backup on iCloud or your computer first. After the reset, restore from your backup. System Data will be recalculated from scratch and is usually much smaller.
For more tips on managing iPhone storage overall, see: How to Free Up iPhone Storage
Summary
"System Data" is a collection of caches, logs, and temporary files that iOS generates during normal use. While iOS is supposed to manage it automatically, it doesn't always keep things tidy. Restarting your iPhone, clearing Safari and app caches, and adjusting iMessage retention are the most effective steps. If all else fails, a backup-and-reset will reliably bring it back under control.
