Apple's built-in storage tools are easy to reach and safe to run, but many Mac users open them expecting a dramatic cleanup and walk away disappointed. Meanwhile, the caches, logs, and app leftovers that actually eat gigabytes sit untouched. This guide compares what Optimize Storage actually does against a thorough manual cleanup, shows realistic before/after numbers for each approach, and tells you exactly which folders to target when the built-in tools aren't enough.
What "Optimize Storage" Actually Does (and Doesn't Do)
On macOS Sonoma, Sequoia, and Tahoe, you reach the storage panel via Apple menu > System Settings > General > Storage. The panel shows a colored bar and four recommendation buttons. The one labeled Optimize Storage does a specific, narrow job: it removes iTunes movies and TV shows you have already watched and keeps only recent email attachments on your Mac rather than the full archive. That is it.
Here is what it does not touch:
- Application caches in
~/Library/Caches - System and kernel extension caches in
/Library/Caches - User log files in
~/Library/Logsand system logs in/var/log - Derived data from Xcode in
~/Library/Developer/Xcode/DerivedData - Orphaned app support folders left behind after you delete an app
- Duplicate files anywhere on the volume
- Large files sitting in Downloads or elsewhere
For someone who streams video rather than buying it, Optimize Storage may recover zero bytes. For someone with a large local iTunes library, it might recover several gigabytes. The variance is enormous, which is why "does Optimize Storage work on Mac?" is such a common search: results are inconsistent because the feature targets a narrow use case.
Before/After Numbers: Optimize Storage vs Manual Cleanup
The table below reflects typical results on a 2-year-old MacBook Pro with a 512 GB SSD that has never been manually cleaned. Your numbers will vary, but the relative pattern is consistent across machines.
| Method | Typical space recovered | Time required |
|---|---|---|
| Optimize Storage (Apple built-in) | 0 to 8 GB (media-dependent) | 2 minutes |
| Clearing user caches manually | 2 to 15 GB | 10 minutes |
| Clearing system and app logs | 200 MB to 3 GB | 5 minutes |
| Removing Xcode derived data | 5 to 40 GB (developers) | 5 minutes |
| Deleting orphaned app support folders | 1 to 10 GB | 15 to 30 minutes |
| Full manual cleanup (all of the above) | 10 to 60+ GB | 30 to 60 minutes |
The pattern is clear: manual cleanup almost always outperforms Optimize Storage in raw bytes recovered, especially on machines used for development, creative work, or heavy browser use. Optimize Storage is not freeing space in many cases because it simply was not designed to handle caches and logs.
The Manual Cleanup Path: Exact Folders and Commands
If you prefer to do this yourself in Terminal or Finder, here is a reliable order of operations.
1. Clear User Caches
Open Finder, press Cmd+Shift+G, and navigate to ~/Library/Caches. You will see folders named after apps: browsers, Slack, Spotify, creative tools, and more. You can delete the contents of individual folders safely. Do not delete the folders themselves, only what is inside them.
In Terminal:
rm -rf ~/Library/Caches/*Note: some apps recreate their cache immediately on next launch, so the gain is most durable for apps you have deleted or rarely use.
2. Clear System-Level Caches
System caches live in /Library/Caches (not the user-level tilde path). Clearing them requires administrator privileges and more caution. A targeted approach is safer than a blanket delete:
sudo rm -rf /Library/Caches/com.apple.dt.Xcode
sudo rm -rf /Library/Caches/com.apple.iconservices.storeRestart after touching system caches so macOS can rebuild what it needs.
3. Trim Log Files
User logs live at ~/Library/Logs. System logs accumulate under /var/log and inside /Library/Logs. Many log files are plain text and entirely safe to delete.
rm -rf ~/Library/Logs/*
sudo rm -rf /var/log/*.log /var/log/*.gz4. Remove Xcode Derived Data and Archives (Developers)
Derived data is consistently one of the largest recoverable categories on developer machines:
rm -rf ~/Library/Developer/Xcode/DerivedData
rm -rf ~/Library/Developer/Xcode/ArchivesYou can also do this inside Xcode: Xcode > Settings > Locations > Derived Data > arrow button > delete.
5. Hunt for Orphaned App Support Folders
When you drag an app to Trash without a dedicated uninstaller, its support folder stays behind at ~/Library/Application Support/. Open that folder in Finder and compare the folder names against your Applications folder. Folders for apps you no longer have are safe to remove. This step is tedious manually, which is why it is often skipped, and why it accumulates.
The "Reduce Clutter" Button: What It Actually Finds
Back in System Settings > General > Storage, the Review Files button (labeled "Reduce Clutter" on older macOS versions) opens a browser that shows large files, downloads, and some application data. It is more useful than Optimize Storage for raw space, but it requires you to manually review and delete each item. It will surface large video files, old disk images, and big downloads, but it does not scan caches or logs. Use it as a complement to manual cleanup, not a substitute.
Why "Optimize Storage Not Freeing Space" Is So Common
The most common reason Optimize Storage appears to do nothing is that the user does not have a local iTunes or TV media library. Apple designed the feature around iCloud offloading: it moves older local media to iCloud and fetches it on demand. If your media is already streaming-only, there is nothing to offload. If you are not signed into iCloud, it will not run at all.
A secondary reason: the storage bar itself can look alarming because of the "System Data" category. System Data on macOS is a catch-all for anything the OS cannot attribute to a specific app category, and it includes caches, virtual memory swap files, Time Machine local snapshots, and iOS device backups. Optimize Storage does not reduce System Data. Manual cache and log cleanup does.
Mac Built-In Cleanup vs a Dedicated App: What to Expect
The core question for anyone comparing the mac built-in cleanup vs an app is how much time and manual effort they want to spend. The built-in tools are safe and free, but they require you to know where to look, make judgment calls about what to keep, and visit multiple locations across Finder and Terminal.
A dedicated tool automates the discovery step: it scans all the relevant paths, shows you exactly what it found and how large each item is, and lets you review the list before deleting anything. The practical value is not just speed. It is completeness. Manual cleanup done carelessly leaves large categories untouched. Manual cleanup done carefully is time-consuming and requires knowing paths most users never visit.
Crumb takes the manual cleanup path described above and runs it automatically, showing you a reviewable list grouped by category (caches, logs, app leftovers, duplicates, large files) with an "is this safe to delete?" explanation for anything that might seem ambiguous. It runs entirely on your Mac with no account needed, so nothing is sent off-device. If you have been relying on Optimize Storage and wondering why your disk is still full, Crumb covers exactly the categories Apple's tool leaves behind.
Which Approach Actually Frees More Space?
The short answer: manual cleanup (or a tool that automates it) almost always recovers significantly more space than Optimize Storage. The built-in feature is not broken, it is just narrow. It solves one problem well: offloading media you already own to iCloud. Everything else, the gigabytes of browser and app caches, the accumulated logs, the orphaned app support folders, requires either a hands-on manual cleanup or a tool designed to handle those paths.
Start with the manual steps above to get a feel for what is on your machine. If you find yourself doing this repeatedly or missing categories, Crumb's whole-disk scan and cleanup checklist make it easier to be thorough without risking something you need.