How to clear disk space on a Mac: finding what actually fills it

The startup disk says there is no room left, an installer refuses to run, and the obvious response is to start deleting. The reason that often frees less than expected is that the Storage screen is a summary, not a map. Learning how to clear disk space on mac properly means measuring before deleting, because the four largest things on a typical Mac are almost never the four things that get deleted first.

Start with the screen, then stop trusting it

On macOS Ventura 13 and later, storage lives in System Settings, under General in the sidebar, then Storage on the right. On older versions it is under About This Mac, then Storage. The bars update automatically as space is freed, so it is worth leaving the window open while working.

Each listed category with a More Info button opens into something actionable, and the categories where that button pays off are Applications, Documents, Messages, Music Creation, Podcasts, Trash, and TV. Those seven are where a sortable list of items appears, which is the difference between a picture of a problem and a way to fix it.

Then there is the category that causes most of the confusion. System Data, called Other on earlier versions, is not a thing that can be cleaned. Apple describes it as a general category measuring space used by Apple and third-party files that do not belong to any more specific category. It is a remainder, not a folder. A large System Data figure is a signal to go looking with a real measuring tool, not an invitation to install something that promises to clean it.

The other reason the screen misleads is timing. Files moved to the Trash still occupy their space until the Trash is emptied, so a session of dragging things to the Trash can leave the number almost unchanged and create the impression that nothing worked.

Measure before deleting

The fastest honest answer to what is taking up space comes from two commands in a terminal, and they take seconds.

df -h
du -xh -d 1 ~ 2>/dev/null | sort -h

The first line reports how full each volume is. The second lists the biggest things one level down from the home folder, smallest first, so the answer is on the last line of the output.

The -x flag keeps the scan on one filesystem, which stops it wandering into mounted volumes. The -d 1 limits it to one level, so the output is a short list rather than a flood. Run it again on whichever line is largest, one level at a time, and the actual culprit usually surfaces in three or four steps. Permission errors on protected directories are normal on a Mac and are what the redirect at the end suppresses.

For anyone who would rather not open a terminal, Finder can do a slower version of the same thing. Select a folder and open Get Info to see its size, or turn on the option to calculate all sizes in the view options for a window so that folder sizes appear in list view. It is slower because Finder computes those sizes on demand, but it works on any Mac without setup.

The point of measuring first is not tidiness. It is that the ranked list is almost always surprising. A single virtual machine image, an old Xcode simulator set, a video project scratch folder, or a node modules directory that was never cleaned up regularly outweighs the entire Downloads folder that most cleanup sessions start with.

There is a second reason to measure rather than to browse. A folder window shows names, and names are a poor guide to size, so scrolling through a home folder tends to produce a decision based on which items look unfamiliar rather than which ones are large. The ranked list inverts that, and it also gives a number to check afterwards. Running the same command again once the deleting is done is the only reliable way to confirm that a session achieved what it seemed to, rather than moving a few hundred megabytes while the real occupant sat untouched two directories down.

Apple's own guidance points in the same direction from the other end, noting that macOS includes utilities to quickly find files taking up space before deleting any of them. Whether the tool is a built-in list or a shell command matters less than the order: find the largest items, then decide, rather than deciding and hoping.

The order that frees the most for the least risk

Once the ranked list exists, work in order of size divided by regret. Things that are large and easily replaced come first.

Target	Why it is first	Where it is
Trash	Space is not released until it is emptied	Trash in the Dock
Downloads	Nearly everything in it can be downloaded again	Dock, or Go then Downloads in Finder
Streamable media	Music, movies, and podcasts can be re-downloaded	The relevant app, or the Storage categories
Old device backups	Superseded iPhone or iPad backups are often several gigabytes each	Storage settings
Unused applications	Large ones bring caches and support files with them	Applications category
Old user accounts	An abandoned account can hold an entire home folder	Users and Groups, then the Users folder

Two items on that list are worth expanding because they are routinely forgotten.

Mail accumulates quietly. Erasing junk mail and then erasing deleted items, both from the Mailbox menu in Mail, releases space that no amount of looking at the Storage screen will explain, because deleted messages behave like the Trash and hold their space until erased.

Old user accounts are the largest single win on shared machines. Removing a user that no longer needs access is one action, but it is worth also checking the Users folder on Macintosh HD afterwards for data belonging to deleted users and for shared files that nobody needs any more. That folder is where leftovers survive an account removal.

Old device backups deserve a second look for the same reason. A Mac used to back up an iPhone or iPad keeps those backups locally, each one running to several gigabytes, and superseded ones are not removed automatically. Deleting old backups is a documented option in the storage settings, and on a machine that has backed up two or three devices over a few years it is frequently the single largest recovery available.

For files that should not be deleted but are rarely opened, compressing them is a middle path. They stay where they are, take less room, and expand again when needed. It suits finished work with a long tail of relevance, such as a delivered project that might be asked about once a year, and it suits collections of many small text files better than it suits video, which is already compressed and will barely shrink.

Caches, and the one safe way to clear them

Third-party cleaners exist to delete caches, and the risk is not that caches are sacred. It is that a tool deciding on its own which support files are disposable will occasionally take something that was not.

macOS has a built-in version of this with a narrow, documented effect: starting up in safe mode clears certain system caches, which are then recreated automatically as needed. Apple frames it as a way to temporarily free enough space to complete a task that needs more room only while it runs, such as installing a macOS update. Leaving safe mode is an ordinary restart.

That framing is the right way to think about cache clearing generally. It buys room for one operation. It is not a durable gain, because a cache that is useful will be rebuilt, and a cache that is rebuilt is using the space again next week. Treating cache clearing as a permanent solution is how a disk ends up needing the same intervention monthly.

Moving files instead of deleting them

Deleting is only one of two ways to get space back, and for anything irreplaceable it is the wrong one.

An external drive takes the largest categories cleanly. Media libraries are the obvious candidates, since photo and video libraries can be genuinely enormous, and both the Photos library and an iMovie library are documented as movable. The thing to get right is moving the library as a unit rather than reaching inside it, because these libraries are bundles that their apps expect to find whole.

The iCloud route works differently: storage is optimized by keeping less-used originals in iCloud and freeing the local copy. That consumes an iCloud storage plan rather than local space, and Apple's own pricing note puts plans starting at 50GB for $0.99 a month in the United States, with prices varying by region. It is worth doing the arithmetic against the size of an external drive before committing to a recurring cost, because for a one-time archive of finished projects a drive is usually cheaper, while for photos that need to stay searchable on a phone the subscription is doing something a drive cannot.

Stopping it from filling up again

A cleanup that is not paired with a rule is a cleanup that gets repeated. Three rules cover most of it.

The first is the Trash. Finder has a setting in its advanced preferences to remove items from the Trash after thirty days, which turns emptying it from a chore into a default. Items removed that way are permanently deleted, so it pairs with having a current backup rather than replacing one.

The second is Downloads. It fills because every browser writes there by default and nothing ever moves things out. The durable fix is a weekly pass with a rule simple enough to apply without thinking, such as keeping anything from the last seven days and anything that has been renamed on purpose, and clearing the rest. A folder that is treated as a staging area stays small. A folder that is treated as storage does not.

The third is projects. Build outputs, dependency directories, virtual machine images, and render caches are the categories that grow without anyone noticing, because they are created by tools rather than by people. A short list of paths to clear when space runs low, written down once, is worth more than any cleaning application, because it encodes which directories are known to be regenerable on that specific machine.

Where the work actually goes

Most of the time in a cleanup is not spent deleting. It is spent going back and forth: a terminal produces a ranked list of paths, and then each path has to be looked at in a folder window to decide whether it can go, which means copying paths between two windows dozens of times in a session.

That is a window arrangement problem rather than a disk problem, and it is why disk cleanups get postponed. Having the measurement and the folder in the same place removes the copying entirely, which is the arrangement described on the Features page, and the differences between that and using Finder next to a separate terminal are set out on the Compared with other file managers page.

What to change first

Before deleting anything, run df -h and then du -xh -d 1 ~ | sort -h, and work down from the largest line rather than starting with Downloads. Then turn on the Finder setting that empties the Trash after thirty days so the easiest win happens on its own. If the back and forth between the ranked list and the folders is what keeps stalling the job, that is the part to change, and Atriens exists to collapse it into one window.