Why your iPhone runs out of space
Apple’s iPhone Storage screen (Settings > General > iPhone Storage) breaks your used space into colour-coded categories: Apps, Photos, Media, Mail, Messages, and a catch-all called System Data. Photos grab attention because the bar is often large, but the real culprits are usually scattered across every other category — cached streaming data, downloaded podcasts nobody finished, years of chat attachments, and app caches that never get cleared automatically.
The good news is you can recover several gigabytes in an afternoon without deleting a single photo. Work through the steps below from top to bottom; each one takes two to five minutes.
Step 1: Check iPhone Storage and offload unused apps
Go to Settings > General > iPhone Storage. Give iOS a moment to calculate everything. You will see a bar graph at the top and a list of apps sorted by size below it. Scroll through and look for apps you haven’t opened in weeks. Tap one and you will see two options: Offload App and Delete App. Offloading removes the app binary but keeps its documents and data on your device, so game saves and offline content survive, and reinstalling from the App Store restores everything. For apps you never plan to use again, tap Delete App. You can also scroll to the bottom and enable Offload Unused Apps so iOS does this automatically when storage runs low.
Step 2: Clear Safari cache
Every website you visit leaves behind cached files, cookies, and history — on a well-used iPhone this can be several hundred megabytes. Go to Settings > Apps > Safari (iOS 18+) or Settings > Safari (earlier). Tap Clear History and Website Data and confirm. This removes cached pages, cookies, and history, but does not delete passwords saved in iCloud Keychain. Note that if you share an Apple ID, the history clears from your other Apple devices too.
Step 3: Delete downloaded podcasts and music
Podcast apps and Apple Music are quiet hoarders — a single downloaded podcast season can consume two or three gigabytes. In Podcasts, swipe left on downloaded episodes and tap Delete Download, or set an auto-delete rule under Settings > Apps > Podcasts. In Music, go to Library > Downloaded Music and swipe to delete albums or playlists. For Spotify or other apps, look in the app’s own settings for a Downloads or Offline Content section.
Step 4: Review large attachments in Messages
Text threads accumulate photos, videos, and voice memos silently. Go to Settings > General > iPhone Storage, tap the Messages entry, then tap Review Large Attachments. iOS lists every attachment sorted by size. Tap Edit, select what you don’t need, and delete. You can also set messages to auto-delete after 1 Year or 30 Days under Settings > Messages > Keep Messages.
Step 5: Optimise iPhone photo storage with iCloud
This addresses photos without deleting any. With iCloud Photos enabled and Optimise iPhone Storage turned on, your device keeps small previews locally while full-resolution originals live in iCloud, downloading on demand when you edit or share. Go to Settings > [Your Name] > iCloud > Photos, make sure sync is on, and select Optimise iPhone Storage. On a device with thousands of 4K videos, the saving can be tens of gigabytes. See more iPhone how-to guides for help choosing an iCloud plan.
Step 6: Empty the Recently Deleted album
When you delete a photo, iOS holds it in a Recently Deleted album for 30 days before removing it permanently — and it still occupies storage until then. Open the Photos app, scroll to Recently Deleted, authenticate, tap Select, then Delete All. The space is freed immediately. A single 4K video can be a few hundred megabytes, so even a handful of clips adds up.
Step 7: Clear individual app caches
iOS has no single ‘clear all caches’ button. The most effective targets are social apps (Instagram, TikTok, Reddit), browsers, and maps apps with offline areas. Some apps include a Clear Cache option in their own settings. For apps that don’t, the quickest method is to offload and reinstall: Settings > General > iPhone Storage, find the app, tap Offload App, then reinstall it. Read our other device guides for more on managing app storage.
Step 8: Tackle System Data
System Data covers temporary files, Siri voices, central app caches, and Safari data, and can balloon to 10 GB or more over years. Remove unused Siri voices under Settings > Accessibility > Spoken Content > Voices, delete offline maps, and restart your iPhone — a simple restart prompts iOS to clear some temporary files. If System Data stays stubbornly large, the most effective reset is a full backup and restore: back up to iCloud or a Mac, then erase the device and restore from the backup. Allow an hour or two; it typically cuts System Data to a few gigabytes.
Troubleshooting
‘Offload App’ is greyed out. System apps Apple bundles with iOS cannot be offloaded or deleted. iPhone Storage says ‘Calculating’ for a long time. Plug the phone in, leave the screen open, and come back in a few minutes; a restart sometimes unsticks it. Optimise iPhone Storage is greyed out. Your library is set to ‘Download and Keep Originals’ or iCloud Photos isn’t enabled — toggle sync off and back on. Space didn’t free up after offloading. Force-close Settings and reopen it, or restart. System Data is still huge after a restart. The backup-and-restore method is the most reliable fix. You deleted something by accident. Check Recently Deleted in Photos — you have 30 days to recover, and deleted apps can be reinstalled with data intact if iCloud backup was on.
