Clean Junk Files from PC and Mac: Free Up Disk Space

Where all that clutter comes from

Nobody deliberately fills a drive with digital junk: it happens one file at a time. Apps leave behind caches so they can launch faster, browsers pile up temporary data from every page visited, the operating system keeps backup copies of updates in case something goes wrong, and the Downloads folder fills with files opened once and never touched again. Any single one of these is small on its own; added together, they can account for a good chunk of the space that seems to have vanished for no reason.

Both Windows and macOS ship with built-in tools built for exactly this, with no need for third-party cleaning software. The underlying logic is the same — find and remove files that no longer serve a purpose — but the approach differs: Windows keeps a long-standing manual tool separate from a newer automatic one, while macOS combines both into a single panel with three switches, plus an automatic cleanup of caches and log files the system runs on its own.

Windows: Disk Cleanup and Storage Sense

Windows offers two distinct routes, and it’s easy to mix them up since they do similar things under different names.

Disk Cleanup is the manual tool that has shipped with Windows for many versions: type its name into the taskbar search bar, pick the drive to scan, select the file categories to remove, and confirm. It’s a one-off action, run whenever it’s needed. On Windows 11, the equivalent feature built into Storage settings is called “Cleanup recommendations.”

Storage Sense, on the other hand, is meant to work automatically in the background, but with a catch that explains why plenty of people assume it’s broken: it’s off by default. It has to be turned on manually from Start > Settings > System > Storage > Storage Sense. Once active, with default settings it clears temporary files and system caches, plus Recycle Bin contents after a period the user can customize; the same applies to files in the Downloads folder that haven’t been opened for a set number of days. One practical limit worth keeping in mind: Storage Sense normally only acts on the system drive (C:), not on other drives connected to the computer.

Practical example: an “insufficient disk space” error that pops up out of nowhere, without the user having downloaded anything, is often tied to the Temp folder filling up with .appx application files from Microsoft Store — one of the typical causes of a full drive, along with system caches and old installation files that Disk Cleanup helps find and remove.

As of Windows 11 version 22H2, if OneDrive is turned on, another mechanism kicks in: local files unopened for 30 days can become “online-only,” meaning they disappear from the local drive to free up space but stay available to download at any time — a change of state that affects only the local copy, not the file itself.

macOS: the Storage panel and the three recommendations

On macOS Ventura 13 and later, the starting point is Apple menu > System Settings > General > Storage (on earlier versions: Apple menu > About This Mac > Storage). The panel shows a breakdown of disk usage by category — Applications, Documents, Messages, Music, Podcasts, TV, Trash, and a general “System Data” entry that covers Apple and third-party system files. For several of these categories there’s also an “More Info” button that shows the detail and lets you act directly.

Beyond manual review, the same panel offers three automatic recommendations, each switchable on its own:

1. Store in iCloud: moves Desktop and Documents files to iCloud Drive, photos and videos to iCloud Photos, and messages and attachments to iCloud, leaving only recent or lightweight versions on the Mac, downloadable on demand.
2. Optimize Storage: automatically removes movies and TV episodes already watched that were bought or rented through Apple TV, and keeps only the most recent email attachments when space is needed.
3. Empty Trash Automatically: deletes items that have been in the Trash for more than 30 days.

Alongside these three named recommendations, macOS handles another part of the cleanup on its own: when the system needs space, it automatically clears caches, log files, interrupted downloads, pending updates, and Safari cache data, without anything to switch on in the Storage panel. It’s a system behavior, not a fourth recommendation with its own toggle.

Windows vs. macOS: same need, two different setups

Aspect	Windows	macOS
Manual tool	Disk Cleanup	Storage panel with per-category detail
Automatic tool	Storage Sense (off by default)	The three optimization recommendations (individually switchable)
Deleted by default	Temporary files, system caches, Recycle Bin contents after a period	Trash emptied after 30 days; caches, logs, and interrupted downloads when space is needed
Practical limit	Normally acts only on the system drive (C:)	Recommendations are switched on individually from the Storage panel
What it does on its own, with nothing switched on	Nothing, as long as Storage Sense stays off	Clears caches, logs, and interrupted downloads when space runs low

Good habits and risks to avoid

A few habits apply to both systems. Checking free space before and after a cleanup — under “This PC” in File Explorer on Windows, in the Storage panel on Mac — makes it possible to confirm what an action actually accomplished. A virus scan, when a drive is full without an obvious explanation, can reveal a cause that’s easy to overlook: malware, too, can take up significant space. And the heaviest media files, like video and photo libraries, are good candidates for moving to an external drive or a cloud service instead of piling up on the local disk, sending the bulkiest data off to remote servers rather than leaving it parked in one place.

One risk deserves particular attention because the mistake can’t be undone: on Windows, the Windows.old folder holds the files from the previous version of the operating system after an update. Microsoft advises against deleting it before 10 days have passed, since until then it’s what allows a rollback if something goes wrong; once removed, that recovery option is gone. Another common mix-up, less serious but frequent, is confusing “Cleanup recommendations” with Storage Sense: on Windows 11 that feature is the counterpart to Disk Cleanup, not to the automatic tool, and anyone who runs it expecting background cleanup ends up still having to launch it by hand.

One last note has more to do with ongoing maintenance than one-off cleanups: turning on Storage Sense on Windows or the optimization recommendations on Mac turns cleanup into a continuous process instead of a chore repeated every time the drive fills up again. The same logic of regular upkeep applies to any home appliance that works automatically: thinking about a robot vacuum cleaner, which needs regular brush checks to keep its motors from overheating, helps frame the same principle applied to a computer’s drive.