What is Other storage on iPhone (System Data) and how to shrink it

Open Settings › General › iPhone Storage and you will see a colored bar. Apps, Photos and Messages have names, and then there is a gray block called System Data that can be a few gigabytes or sometimes more than 50. It is the most confusing part of iPhone storage, because Apple gives no list of what is inside. This guide explains what it contains, why it grows and eight things you can do to make it smaller, in order from easy to heavy.

What is System Data (Other) on an iPhone?

System Data is everything that iOS does not label as an app, a photo, media or a message. It includes cache files from apps and websites, logs and diagnostics, downloaded Siri voices and keyboard dictionaries, temporary update files, and the system's own working space. It is normal for it to grow when you use the phone, and it should shrink when iOS cleans up. Some items are needed and cannot be removed. Others are leftovers that iOS clears when it is low on space.

How to see how much you have

Why System Data gets so large

• Streaming and downloads: video and music apps cache a lot of data.
• Safari and app caches: websites and apps store files to load faster.
• A recent iOS update: update files and temporary data can remain for days.
• Messages and attachments: some of this shows up here, especially on older iOS versions.
• A bug or a stuck process: occasionally iOS fails to clean up, and System Data balloons for no clear reason.
• Being nearly full: when free space is very low, the phone cannot clear caches properly.

8 ways to shrink System Data

How to back up and restore to clear System Data

If System Data stays huge after the other steps, a backup and restore is the most reliable fix. First make a full backup to a computer or to iCloud, and check that it finished. See how to back up an iPhone. Then erase the iPhone at Settings › General › Transfer or Reset iPhone › Erase All Content and Settings, and restore from the backup during setup, see how to restore an iPhone from backup. Do not skip the backup, and do not erase the phone before you are sure it is complete.

Things that do not work

• Apps that promise to clean Other storage with one tap. Most do nothing or sell you a subscription.
• Force quitting apps. It does not clear storage.
• Resetting all settings. It does not remove System Data, and it clears useful settings.
• Waiting for a month. Some System Data clears itself, but a stuck cache will not.

System Data is large right after an update

After a major iOS update, System Data is often much bigger than normal. The phone keeps copies of files while it installs, and it indexes photos, messages and other content in the background. This can take a day or more, especially on an older iPhone. Leave the phone plugged in on Wi-Fi overnight with the screen locked, and restart it in a day or two. If it is still huge after a week, use the steps above.

When the problem is the phone's size, not the system

If you have a 64 GB or 128 GB iPhone and keep running out of space, the real answer may be to move photos and videos off the phone. Turn on iCloud Photos with Optimize iPhone Storage, or copy photos to a computer. If you do not have enough iCloud space, see how much iCloud storage you need. A phone with at least a tenth of its space free runs better and gives iOS room to clean up after itself.