Mac storage recommendation categories before deleting large system data files

Checking Which Storage Category Holds the Most Space

Open the storage screen by going to About This Mac and clicking the Storage tab. The colored bar splits your drive into categories like Applications, Documents, System Data, and Others. The largest section gives the first clue about where to focus the cleanup effort.

System Data, sometimes labeled as System or Other, often surprises users because it can reach tens of gigabytes without warning. Checking this category first helps decide whether a targeted cleanup is needed or whether the space is mostly taken by app caches and temporary files that macOS manages on its own.

Comparing System Data with User-Filled Categories

System Data usually contains cached files, logs, temporary downloads, Time Machine snapshots, and old iOS backups. User-filled categories such as Documents, Photos, and Applications are easier to review because you can open each folder and decide what to keep or move to external storage.

If System Data is smaller than Documents or Applications, you may not need to touch system files at all. Focus on clearing out duplicate downloads, old screen recordings, or large media folders that you no longer need rather than risking the removal of system caches that may affect app behavior.

Check for Large Files That Commonly Fill Up System Data

Before trying to free up space from the System Data category on your Mac, it’s worth identifying the items that are known to grow over time. In many cases, the storage isn’t being used by mysterious system files but by temporary data that has accumulated through normal use.

One example is Time Machine local snapshots. If Time Machine is enabled, macOS may keep temporary backup snapshots on your internal drive whenever your backup disk isn’t available. These snapshots are helpful because they allow you to restore recent versions of files, but they can also take up several gigabytes of storage.

If you’re comfortable using Terminal, you can view the snapshots by running:

tmutil listlocalsnapshots /

When you confirm that older snapshots are no longer needed, you can remove them with the appropriate tmutil command. Only use this method if you’re familiar with Terminal, since command-line tools should always be used carefully.

Another place that’s often overlooked is old iPhone or iPad backups. If you’ve backed up Apple devices to your Mac over the years, those backup files can continue occupying storage long after the devices are no longer in use. Open Finder, locate the backup management section for your devices, and review the list of saved backups. Deleting copies that you no longer need can recover a surprising amount of disk space without affecting your current Mac.

Let macOS Handle the Safe Cleanup First

If you’re unsure which files belong in System Data, avoid deleting folders manually. Many of those files are created by macOS or by applications while they’re running, and removing the wrong items can cause unexpected problems.

A safer approach is to use the storage management tools that are already built into macOS. Open About This Mac > Storage, then select Manage to review Apple’s cleanup recommendations. You’ll usually find options to empty the Trash automatically, identify large files, remove applications you no longer use, and review documents that are taking up significant space. These suggestions focus on files that are generally safe to remove without affecting the operating system.

After you’ve finished cleaning up, restart your Mac before checking the storage information again. A restart gives macOS the chance to clear temporary files, rebuild storage calculations, and remove cached data that may still be listed while the system is running. It’s common to see the System Data category become smaller after a restart, even if you haven’t manually deleted anything else.

Making a habit of reviewing storage with Apple’s built-in tools from time to time is usually more effective than trying to clear the entire System Data category yourself. It reduces the risk of deleting important files while still helping you recover storage in a safe and predictable way.

FAQ

Question: How do I know which files inside System Data are safe to delete?
Answer: Open the Storage screen and click the Manage button to see system-recommended cleanup options. Avoid deleting files from the System Data folder manually unless you recognize the file name and purpose, because removing cache or log files can cause unexpected app behavior.

Question: Will deleting Time Machine local snapshots affect my backup history?
Answer: No, local snapshots are temporary copies stored on your Mac between backup cycles. Deleting them frees space without removing any backup data from your external Time Machine drive. Use the Terminal command listed in the article to check and delete only the snapshots you no longer need.

Question: Why does System Data grow back after I clean it?
Answer: macOS recreates cache files, logs, and temporary data as apps run and system processes operate. A stable System Data size around 10 to 15 GB is normal for most Macs. If the category grows unusually large, check for stuck downloads, unfinished updates, or a full Trash that has not been emptied.