How to Reclaim System Data on Mac (Updated for macOS 27)

Running low on storage is still one of the most common frustrations on a Mac. Most of the time, the biggest unexplained category is System Data (previously called “Other”).

After a major macOS upgrade—especially macOS 27 Golden Gate—this category frequently jumps without an obvious reason. We have seen machines report 18–30 GB of System Data even when users had not added large new apps, well above Apple’s stated figures for Apple Intelligence models. Local AI tools can add even more.

In this guide we explain what System Data actually contains, why it grows after upgrades, and the practical steps we use to reclaim space safely.

RELATED: The Best System Monitor Apps to Check Your Mac’s Performance

What is System Data / Other storage

Both “Other” and “System Data” refer to the same broad category that holds miscellaneous files the system does not classify elsewhere. Typical contents include:

• Apple Intelligence and on-device Siri models
• Local Time Machine snapshots
• System and app caches
• Logs and diagnostic reports
• iOS/iPadOS device backups stored on the Mac
• Leftover files from deleted applications
• Virtual machine and container data
• Temporary files created during updates

Apple intentionally keeps the category somewhat opaque. That design protects critical system files, but it also makes it harder to see which parts are safe to remove.

Why system data grows after a macOS upgrade

Major upgrades are the most common trigger. During and after installation the system downloads new components, rebuilds caches, creates temporary files, and (on macOS 27) pulls down Apple Intelligence models. Some of those models appear even if you never enable the new features.

Third-party local AI tools compound the problem. A single quantized language model can occupy 10–40 GB. Dictation apps sometimes ship their own speech models ranging from under 1 GB to more than 15 GB. These files rarely show up clearly in the basic Storage view, so they inflate the overall picture.

Older sources of bloat still exist too: accumulated caches, old local snapshots, and leftover support files from apps you removed months ago.

How to check system data size

The process is straightforward on current macOS versions:

• Open System Settings.
• Go to General → Storage.
• Wait for the categories to finish calculating.
• Look at the System Data figure (and any separate Apple Intelligence entry if it appears).

Hovering over the storage bar still shows the approximate size. We recommend taking a screenshot before you start cleaning so you can measure the real difference afterward.

Bonus tip: Visual disk tools such as DaisyDisk remain useful for seeing large folders that the basic Storage view does not explain clearly. DaisyDisk scans your disks and presents a visual map so you can identify oversized items before deleting them.

How to clear System Data storage

Clearing System Data does not require expensive software or risky terminal commands. We use a layered approach that prioritizes the biggest new sources of bloat first.

1. Inventory local AI models (highest impact on macOS 27)

Many of the largest unexpected files in 2026 are local language or speech models. General cleaners often miss them or treat them as ordinary large files.

We use What The Model, a free open-source native Mac utility that scans for models across Ollama, Hugging Face caches, LM Studio, GGUF/Safetensors, MLX, GPT4All, Jan, and other common sources. It shows size, location, completeness, and ownership, then lets you preview cleanup actions that move files to the Trash.

• GitHub: https://github.com/powtac/wtm
• Project site: https://powtac.github.io/wtm
• Releases: https://github.com/powtac/wtm/releases

Run a full scan, sort by size, and remove models you no longer need. This step frequently recovers the biggest blocks of space that other methods overlook.

2. Optimize storage with the built-in Mac tools

Before installing anything else, use the free tools Apple already provides.

Open System Settings → General → Storage and review the recommendations. You can enable Optimized Storage features, manage iCloud content, empty the Bin automatically, and reduce clutter. These options are safe and worth trying first.

3. Review local Time Machine snapshots

Time Machine local snapshots can consume significant space. They are useful for recovery, but they contribute to System Data.

You can list them in Terminal with:

tmutil listlocalsnapshots /

Only delete snapshots if you understand the implications. In many cases the system manages them automatically once free space becomes limited. You can also exclude large folders from future backups in Time Machine settings to limit growth.

4. Clear caches and leftovers with Finder (careful approach)

Open Finder and press Shift-Command-G, then go to:

• ~/Library/Caches
• ~/Library/Logs
• ~/Library/Application Support (look for folders belonging to apps you have already deleted)

Move items to the Trash rather than deleting them immediately. Avoid removing anything you cannot identify. Adobe caches (Photoshop, After Effects, etc.) are common space consumers and can usually be cleared safely if you do not need the old render files.

5. Review iCloud Drive and device backups

iCloud files that are downloaded locally can appear under System Data or related categories. You can manage what is stored on the Mac in System Settings → Apple ID → iCloud.

Old iOS/iPadOS backups stored on the computer are also worth checking and removing if you no longer need them.

6. Use a trusted third-party cleaner for the remaining junk

If you prefer not to hunt through folders manually, a good cleaner can speed up the process. We now recommend starting with free and open-source options before considering paid tools.

See our updated roundup:

→ Best Free Open-Source Mac Cleaners

These tools handle caches, logs, and app leftovers effectively. For duplicate files that also pressure storage, see:

→ Best Duplicate File Finders for Mac

Paid suites such as CleanMyMac remain capable, but many users can recover substantial space with free tools plus the model inventory step above.

7. Restart and re-measure

Restart the Mac, return to System Settings → General → Storage, and compare the new System Data figure with your earlier screenshot. The category can take a few minutes to update.

What usually comes back

Some space recovered from Apple Intelligence models may return. On macOS 27 the system can treat certain on-device models as required and redownload them. Third-party models stay deleted unless you reopen the related apps and choose to download them again. Local snapshots can also reappear as Time Machine continues normal operation.

The realistic goal is not zero System Data. The goal is to remove the unnecessary bulk so the category returns to a more reasonable size for your machine.

FAQs

How do I find out how much System Data is using?

Go to System Settings → General → Storage. The System Data category (and any Apple Intelligence entry) will be listed once the calculation finishes.

Will deleting System Data on my Mac affect my iPhone?

No. Most System Data is local to the Mac. iCloud-synced content is the main exception, and even then only the locally downloaded copies are affected.

Is it safe to delete everything under System Data?

No. Some files are required by macOS. That is why we recommend a layered approach: identify large AI models first, clean obvious caches and leftovers next, and avoid deleting anything you cannot recognize.

How can I keep System Data from growing again?

Be selective about local AI models, run occasional cleanups, empty the Trash regularly, and review Storage Settings after every major macOS upgrade.

Final thoughts

System Data will probably always remain partly mysterious. In 2026 the combination of Apple Intelligence models and the growing number of local AI tools has made the category larger and less transparent than before, especially right after a major upgrade.

The most effective approach we have found is measured and layered: check the current size, inventory AI models with a purpose-built tool, clean ordinary junk with a trusted utility, review snapshots and backups, then re-measure. Used this way, most Macs can reclaim a useful amount of space without aggressive or risky deletions.

If your System Data figure climbed after upgrading to macOS 27 (or any recent major release), start with a clear measurement and a model scan. That combination usually reveals the largest recoverable pieces faster than running a generic cleaner alone.

READ ALSO:

• MacBook Air and MacBook Pro Overheating
• macOS Upgrade – Not Enough Free Space. How To Fix?
• How to Fix ‘Disk Utility Can’t Repair This Disk’ Error
• How to Fix macOS VPN Not Working
• More Mac Performance-related Tips

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