How to Check iPhone Storage and Understand Every Category

By Matthieu Poulain · Updated September 26, 2026 · 6 min read

To check your iPhone storage, open Settings > General > iPhone Storage. A colored bar shows how much space you've used and what's using it, and below it every app is listed from largest to smallest. Tap any app to see how much is the app itself and how much is its data.

How to check iPhone storage in Settings

1. Open the Settings app.
2. Tap General.
3. Tap iPhone Storage. It can take a few seconds to calculate, and the numbers may shift while it does.
4. Read the bar at the top: it shows used space out of your total capacity, split by category.
5. Scroll down to see recommendations, then the list of apps sorted by size.

If you only need the headline numbers, Settings > General > About shows your total Capacity and how much is Available.

What each storage category means

The bar groups your data into categories. Their names vary slightly between iOS versions, but these are the ones you'll see most.

What is System Data on iPhone?

System Data used to be called "Other". It holds caches, logs, temporary files and resources such as Siri voices. It's normal for it to grow and shrink over days, because iOS creates these files as you use your phone and purges them when space gets tight.

You can't delete System Data directly, but a few things often bring it down:

• Restarting your iPhone.
• Clearing Safari's history and website data.
• Deleting large message threads.
• Installing the latest iOS update.

If it stays unusually large after all of that, the last resort is to back up, erase the iPhone and restore from the backup.

What is the iOS category?

This is the operating system. Its size depends on your iOS version and model, and it can't be reduced. It's also why a phone sold with a given capacity never shows that full amount as free space.

Reading an app's storage: App Size vs Documents & Data

Tap any app in the list and you'll see two numbers.

• App Size is the app itself, the part you download from the App Store. This is what people mean when they ask about "Applications" in iPhone storage.
• Documents & Data is everything the app has saved since: caches, downloads, offline files, chat media.

Below those numbers are two buttons. Offload App removes the app but keeps its documents and data, so reinstalling it restores everything. Delete App removes both.

When Documents & Data is much bigger than App Size, the app is holding a lot of cache. Check the app's own settings for a clear-cache option. If there isn't one, deleting and reinstalling the app resets it, as long as anything important is backed up or synced first.

Checking your Photos storage

Tap Photos in the list to see how much space your library takes. On this screen iOS may also point to Recently Deleted, which keeps deleted photos and videos for 30 days and still counts against your storage until it's emptied.

What iPhone Storage won't tell you is which photos and videos are the heaviest. That matters, because a few long videos can outweigh thousands of photos. PhotoTri has a Storage screen that splits your library into photos and videos and lists your biggest files, so you can see what's worth deleting. The sizes it shows are estimates, but they're enough to spot the outliers.

If Photos is your biggest category, our guide on how to free up space on iPhone ranks the fixes by how much space they save.

iPhone storage vs iCloud storage

These are two different things, and mixing them up is behind many storage headaches.

• iPhone storage is the physical space on your phone. Check it in Settings > General > iPhone Storage.
• iCloud storage is your online space, 5 GB free, with more available through iCloud+. Check it in Settings > [your name] > iCloud.

Upgrading your iCloud plan doesn't free space on your iPhone on its own. It only helps if you use iCloud Photos with Optimize iPhone Storage turned on, which keeps smaller copies on the phone and the originals in iCloud.

Why the numbers keep changing

Don't worry if your storage total moves a little from one day to the next. Caches grow as you browse and stream, iCloud Photos downloads and removes full-size originals in the background, and iOS clears temporary files when it needs room.

What matters is the trend. If free space keeps shrinking week after week, the list of apps and the Photos entry will show you where it's going. Checking once a month takes a minute and gives you time to act before the "Storage Almost Full" warning shows up.

What to do with what you found

Once you know where your space goes, the fix is usually obvious. Photos at the top means sorting videos and duplicates. One oversized app means offloading it or clearing its cache. A huge System Data means a restart and an update first.

If you're already getting warnings, start with our guide to what to delete when iPhone storage is full.