External drive full but no files? Where the space went

An external drive full but no files on your Mac almost always means the space is in something Finder doesn't show as files. The usual places are the drive's own hidden Trash, Time Machine backups or APFS snapshots on it, or another volume that shares its space. Each one shows up in Disk Utility, and none needs Terminal.

Start with the Trash. Files you delete from an external drive stay on that drive, in a hidden folder, until you empty the Trash while the drive is connected. Eject it first and the space stays used, even though the Trash looks empty once the drive is gone.

If emptying the Trash doesn't help, open Disk Utility, choose View › Show All Devices, and select the drive. The bar and the volumes under it show whether a backup volume, a snapshot or a second partition is using the room. The rest of this post goes through each cause in turn.

Less often, the cause is the drive's format: exFAT stores small files in large blocks, and the hidden files macOS and Windows add can pile up. A damaged directory, which First Aid can repair, is the rarest cause.

External drive full but no files on a Mac: the usual causes

Finder adds up the files it shows you. A drive's used space includes everything else as well: deleted files waiting in a Trash, backups and snapshots, other volumes, hidden system folders and the file system's own bookkeeping. When those are large, the drive looks full of nothing.

Where the space is	What you notice	Where to check
The drive's own Trash	You deleted files from it recently	Empty the Trash with the drive connected
Time Machine backups	The drive is, or was, a backup disk	Disk Utility's volumes and snapshots
APFS snapshots	Deleting files frees nothing	View › Show APFS Snapshots
Another volume	The free space is low on every volume	View › Show All Devices
Hidden system folders	The used space grows with no new files	Show hidden files in Finder
Small files on exFAT	Many small files, much more used	Get Info: size against size on disk
A damaged directory	The numbers never change	First Aid in Disk Utility

Which number says the drive is full?

Select the drive in the Finder sidebar and choose File › Get Info. The General section lists its Capacity, Available and Used space, and its Format. Write the used figure down; it's the number you're trying to explain.

Then select the drive's icon, open it, and press Command-A to select everything at the top level. Option-Command-I opens the Inspector, which adds up the selection. If that total is far below the used figure, the space is in one of the places above.

Why doesn't Finder show the files?

Some are hidden on purpose: their names start with a period, and Finder doesn't show those by default. Others aren't files at all in Finder's sense. A snapshot or a second volume takes space on the drive without appearing in any folder you can open.

And some belong to someone else. Files another user account trashed, or a Windows PC's Recycle Bin, sit in folders your account can't always open.

The drive's own Trash still has the files

This is the most common cause, and the easiest to fix. Deleting a file only moves it to the Trash, and the Trash for an external drive lives on that drive.

Where do files deleted from an external drive go?

When you move an item to the Trash, it goes to a hidden .Trashes folder at the top of the disk it came from, with a separate folder inside for each user account. The catalog's entry for the Trash describes both places, and says the space isn't available again until the Trash is emptied.

Your Trash in the Dock shows those items while the drive is connected. Eject the drive and they vanish from the Trash window, but they're still on the drive, taking the same space.

How do you empty an external drive's Trash?

1. Connect the drive, and wait until it appears in the Finder sidebar.
2. Click the Trash in the Dock and look through what's there. Use File › Put Back for anything you still want.
3. Choose Finder › Empty Trash, or click Empty at the top right of the Trash window, and confirm.
4. Check the drive's Get Info again before you eject it.

Emptying is permanent: Finder can't bring the items back afterwards. If the Trash refuses to empty, the post on why the Trash won't empty goes through each message and its fix.

Why is the space still used after emptying the Trash?

Some people report that emptying from the Dock seemed to leave an external drive's Trash full, and that Finder › Empty Trash with the drive connected worked. If the space doesn't come back either way, three causes are common:

• Another account's folder. Items another user trashed sit in that user's own folder inside .Trashes. Ask them to connect the drive and empty their Trash.
• Another Mac. The folder inside .Trashes is named after the account's number. An account with a different number on another Mac leaves its items in a folder you won't see.
• A snapshot. If the drive is APFS and something made a snapshot before you deleted the files, the snapshot still holds them. That's the next section.

Can you look inside .Trashes yourself?

You can see it: press Command-Shift-Period in Finder to show hidden items, and the post on hidden files on a Mac explains what else that reveals. Finder usually won't open other accounts' folders inside it, because macOS keeps them private.

Don't drag the .Trashes folder itself to the Trash, and don't paste removal commands from a forum. Commands that delete don't use the Trash, so one typo can erase the wrong folder with no way back.

Time Machine backups and APFS snapshots on the drive

If the drive is formatted as APFS, or has ever been a backup disk, snapshots and backups are the next place to look. They take real space and never appear as files you can select in Finder.

Is the drive your Time Machine backup disk?

Apple's guide says the entire APFS volume used for Time Machine is reserved for its backups. Apple also says Time Machine keeps hourly backups for 24 hours, daily backups for a month and weekly backups for all previous months, and deletes the oldest only when the disk is full.

So a backup disk that's nearly full is working as designed. Time Machine fills it, then makes room by itself. The post on a full Time Machine disk covers when that becomes a problem and what to do about it.

Did you add a backup volume to a drive you also use for files?

Apple describes this setup: to keep other files on a Time Machine drive, add a second APFS volume in Disk Utility, and the two volumes then share the available space. That's convenient, but it means backups can grow until the files volume has almost nothing left.

Finder then shows your files volume with little in it and almost no space available. Disk Utility shows why: the space is in the other volume, under Other Volumes in the container's bar.

How do you see snapshots on an external drive?

1. Open Disk Utility, from the Utilities folder in Applications.
2. Choose View › Show APFS Snapshots.
3. Select the drive's volume in the sidebar. A table at the bottom of the window lists its snapshots.
4. Click the More menu and choose Show Columns to add Private Size and Cumulative Size.

If the list is empty, snapshots aren't the cause. The post on APFS snapshots explains the names you'll see and why one snapshot's size rarely says what deleting it frees.

Who makes snapshots on a drive that isn't a backup disk?

Two things, usually. Time Machine makes a local snapshot of each volume it backs up, right before each backup, and deletes it after 24 hours, as Howard Oakley's study of Time Machine describes. So an APFS drive included in your backups holds deleted files for up to a day.

Backup and cloning apps can also keep snapshots on drives they copy to or from, on their own schedule. They hold deleted files the same way, often for longer.

How do you get the space back from snapshots?

Snapshot	Who made it	How to remove it
A Time Machine backup	Time Machine, on its backup disk	Time Machine deletes old ones when the disk is full
A Time Machine local snapshot	Time Machine, before a backup	Wait a day, or turn off automatic backups for a while
A backup app's snapshot	That app	Change how long it keeps them, in that app
One you don't recognize	Unknown	Leave it, or delete it alone in Disk Utility

To remove a single snapshot, select it in Disk Utility's table and click Delete Snapshot. You can no longer restore anything from it afterwards. For whole backups, use Time Machine's own controls rather than Finder; the post on deleting Time Machine backups shows how on current macOS.

Another volume is sharing the drive's space

APFS lets one partition hold several volumes, and they all draw on the same pool of free space. That's flexible, and it's also the most confusing cause of a drive that looks full.

What is an APFS container?

Apple's guide to file system formats says the volumes in an APFS container share its free space, which is allocated to each volume as it needs it. The container is the partition; the volumes are what you see in Finder.

So each volume reports the same free space: whatever the container has left. A volume holding 50 GB can show almost nothing available, because a neighbour holds the rest.

How do you see every volume on the drive?

1. Open Disk Utility and choose View › Show All Devices. The sidebar then shows each drive, its containers and their volumes.
2. Select the container under your drive. Its bar shows how much each volume uses.
3. Select each volume in turn and note its Used figure.

Apple's guide says the default view, Show Only Volumes, lists just the volumes, and some tasks are possible only with all devices shown. Leave it on while you investigate.

What do Used, Other Volumes and Free mean?

When you select a volume, Disk Utility's bar splits the container into Used for that volume, Other Volumes for every other volume in the same container, and Free. A large Other Volumes figure on a drive you thought held one volume is your answer.

What Disk Utility shows	What it means for your drive
A container shared by two or more volumes	They all draw on the same free space
Large Other Volumes	Another volume holds the space, often backups
A volume shown dimmed	It exists but isn't mounted, and still takes space
More than one container	The drive is partitioned; each part is separate
Purgeable in the Info window	Space macOS can free, counted as available

What about a volume that isn't mounted?

A volume that isn't mounted doesn't appear in Finder at all, but its data stays on the drive. Disk Utility lists it, dimmed. Select it and click Mount to look inside before you decide anything.

Don't delete a volume you don't recognize. Deleting a volume erases its data permanently, and an unfamiliar name is often a backup volume or something another Mac created.

Is the drive split into partitions?

A drive can also be divided into separate containers or partitions, each with its own fixed size. Apple's partitioning guide says that in most cases you shouldn't partition a disk, and suggests several APFS volumes in one partition instead.

If your drive has a second partition, perhaps formatted for Windows, its space is out of reach of the volume you use. The sidebar shows it under the drive. Removing or resizing a partition erases data, so copy what you need first.

The guide to Disk Utility for storage covers partitions, volumes and their size options in detail.

Hidden system folders that macOS keeps on the drive

macOS puts a few hidden folders at the top of most drives it uses. They're normally small, but two of them can grow, and both are managed by macOS rather than by you.

Which hidden folders does macOS create on a drive?

The ones you're most likely to find, once hidden files are showing:

• .Trashes: the drive's Trash, one folder per user account.
• .Spotlight-V100: Spotlight's index of the drive, so searches can find files and what's inside them.
• .fseventsd: a record of changes to files, which apps such as backup tools use to see what's new.
• .DocumentRevisions-V100: earlier versions of documents saved by apps such as Pages, TextEdit and Preview.

The catalog matches three of them on any connected drive, not only on your Mac's own disk: the Trash, the Spotlight index and document versions. All of them belong to macOS, so the fixes below work through macOS rather than through Finder.

Can the Spotlight index fill a drive?

It's usually a small part of the drive. The catalog's entry for the Spotlight index notes that some people have seen it grow to well over 100 GB when indexing goes wrong. The post on the Spotlight index explains why.

Apple's way to fix it is to rebuild it, not to delete it in Finder:

1. Choose Apple menu › System Settings, then click Spotlight in the sidebar.
2. Click Search Privacy, then add the drive with the add button.
3. Wait a few seconds, select the drive in the list, and click the remove button.
4. Click Done. Spotlight indexes the drive again.

If you never search an external drive, such as a backup or an archive, you can simply leave it on the Search Privacy list. Spotlight then doesn't index it.

What about document versions?

The document versions folder grows when you edit large documents often on that drive. Only macOS changes it. To remove a version, open the document, choose File › Revert To › Browse All Versions, select the version, then choose Delete This Version from the same menu.

What are the ._ files on an exFAT or FAT drive?

On drives formatted as exFAT or MS-DOS (FAT), macOS can't store some Mac file information the way APFS does. So for files that carry it, it writes a small companion file named with a period and an underscore in front. Finder hides them; Windows shows them.

Each one is tiny, but they can double the number of files on the drive. On exFAT, that matters more than it sounds, as the format section below explains.

Files left by Windows and other computers

A drive that has been plugged into a Windows PC carries folders from Windows too. They're hidden on a Mac in the same way, and they can hold real space.

What is the $RECYCLE.BIN folder?

Windows keeps deleted files in a hidden $RECYCLE.BIN folder on the drive they came from, much as macOS uses .Trashes. Microsoft's support forum describes one per drive, including external ones. Files someone deleted on a PC stay there until that PC's Recycle Bin is emptied.

The cleanest fix is to connect the drive to the PC, open Recycle Bin, and empty it there. Removing the folder from a Mac also erases whatever the PC's users might still want back.

What is System Volume Information?

It's a folder Windows creates on drives, which Microsoft's support forum describes as used by System Restore and for information about the drive. It's normally small on an external drive. If it's large, manage it from Windows rather than deleting it from your Mac.

Can other devices leave files behind?

Yes. Cameras, game consoles, TVs and other computers can each create their own hidden folders on a drive. Look at what's in a folder before you remove it, and when it belongs to a device, use that device's own option to delete recordings or caches.

Folder on the drive	Created by	Where to clear it
.Trashes	macOS	Empty the Trash on the Mac, drive connected
.Spotlight-V100	Spotlight	Search Privacy in Spotlight settings
.DocumentRevisions-V100	macOS versions	Browse All Versions in the app
$RECYCLE.BIN	Windows	Empty the Recycle Bin on the PC
System Volume Information	Windows	Leave it, or manage it from Windows

exFAT and allocation units: when small files take more room

If your drive is formatted as exFAT, so it works with both Macs and PCs, the format itself can make files take more space than their contents. It doesn't hide space, but it can make a drive with modest files fill much sooner than you'd expect.

What is an allocation unit?

exFAT divides the drive into fixed-size clusters, also called allocation units, and stores each file in whole clusters. Microsoft's exFAT specification allows clusters from one sector up to 32 MB, and a file that isn't empty takes at least one.

So with large clusters, a 2 KB text file takes a whole cluster. Thousands of small files, plus a companion ._ file for each, can use many times their own size.

How do you see the effect in Finder?

Select a folder of small files on the drive and choose File › Get Info. The Size line shows two numbers: how much data the files hold, and in brackets how much space they take on disk. A large gap on an exFAT drive is the cluster size at work.

Can you change the allocation unit size on a Mac?

Not in Disk Utility. Its Erase window asks for a name, a format and a scheme, with no setting for cluster size, and Apple doesn't document the size it picks. Changing the cluster size means erasing the drive anyway, so copy everything off first.

Apple's guide suggests exFAT for Windows-compatible drives over 32 GB, and MS-DOS (FAT) for 32 GB or less. If the drive only ever meets Macs, APFS avoids the problem. The post comparing APFS and exFAT goes through which to choose for each kind of drive.

Disk images, sparse bundles and packages

Some single files are really containers of other files. They show their size honestly in Finder, but people often forget they're there, or expect them to shrink when they delete what's inside.

Why does a disk image take so much space?

Apple's Disk Utility guide says an image made from a whole device includes its free space: an 80 GB device holding 10 GB of data makes an 80 GB image. An image made from a folder includes only the data. A few old device images can fill a drive quickly.

Why didn't a sparse bundle shrink?

A sparse bundle is a read-write image that, in Apple's words, grows with the data stored in it. It's common for backups over a network. Apple's guide doesn't say it shrinks when you delete files inside it, so expect the bundle to stay at its largest size.

Disk Utility's Images › Resize can make some images smaller, and Apple notes that not every image format supports resizing. Eject the image first, as Apple's steps say.

What about libraries that look like one file?

The Photos library, a Final Cut Pro library or a virtual machine's disk appear in Finder as single items, and each can be very large. Their size shows in Get Info, so they're easy to find.

Manage them in their own app. Don't open a Photos library's package and remove things inside it in Finder. Apple's Photos guide says not to access or alter a library's contents in the Finder, to avoid deleting or damaging it.

A damaged directory: when First Aid is the fix

Occasionally, the file system's own records are wrong. The drive then reports space as used that no file holds, or the numbers don't change no matter what you delete. That's what Disk Utility's First Aid checks for.

When should you suspect damage?

When you've emptied the Trash with the drive connected, found no snapshots and no other volumes, and the used figure still doesn't move. Other signs are files that won't copy, errors when you open folders, or a drive that sometimes refuses to mount.

How do you run First Aid on an external drive?

Apple's steps work from the inside out:

1. Open Disk Utility and choose View › Show All Devices.
2. Select the drive's first volume, click First Aid, then Run, and follow the prompts. Repeat for each volume.
3. Select the container and run First Aid on it.
4. Select the drive itself, at the top of its list, and run First Aid once more.

Apple says Disk Utility can't detect or repair every problem a disk may have. Copy anything important before you start, if the drive still lets you.

What if First Aid reports overlapped extent allocation?

Apple says this means two or more files occupy the same space, so at least one is likely damaged. Many of the affected files get aliases in a DamagedFiles folder at the top of the drive. Replace the ones you can, and open the rest to check them.

If a repair fails, Apple says to try again, and if it still fails, to back up as much as you can, erase the drive and restore your files. If Disk Utility says the disk is about to fail, back it up and replace it.

Reading Finder's and Disk Utility's numbers side by side

Finder and Disk Utility can disagree about the same drive, and each disagreement points to a cause. The guide to why the storage numbers differ covers the Mac's own disk; external drives follow the same rules.

Where you look	What it counts	What it misses
Inspector on everything you can see	Visible files and folders	Hidden folders, snapshots, other volumes
Get Info on the drive	Capacity, available and used	Which volume or snapshot uses it
Disk Utility's bar	Used, other volumes and free	What's inside each volume
Disk Utility's Info button	Available, with free and purgeable apart	Snapshots by name
Disk Utility's snapshot table	Each snapshot and its sizes	What the snapshot holds

Why does Finder show more available than Disk Utility's free?

Finder's available figure includes purgeable space, which macOS can free when it needs to, such as space held by Time Machine's local snapshots. Disk Utility's Info button shows available space split into free and purgeable. Before a large copy, trust the free figure.

Why does a new drive show less than its box says?

Drive makers count 1 GB as 1 billion bytes. Apple says only OS X Leopard and earlier counted in binary units, so a Mac today uses the same units as the box. The small difference you see is mostly the space formatting and the file system take.

Tools that count 1 GB as 1,073,741,824 bytes make the same drive look about 9% smaller at terabyte sizes. That's a difference in units, not missing space.

Why does the used space change after you eject and reconnect?

macOS can update a drive's figures in the background, and freeing space held by a snapshot or a deleted file isn't always instant. Check again a few minutes later, then once more after reconnecting. A figure that never moves points back to First Aid.

Checking a full drive, step by step

Here's the whole check in order, cheapest first. The steps follow macOS 27 Golden Gate, and none of them needs Terminal.

The order to work through

1. Measure. Get Info on the drive for its used space, and the Inspector on everything you can see.
2. Empty the Trash with the drive connected, then measure again.
3. Look for volumes. Disk Utility, View › Show All Devices, then the container's bar.
4. Look for snapshots. View › Show APFS Snapshots, then each volume.
5. Show hidden files with Command-Shift-Period, and check the large hidden folders.
6. Check small files on exFAT with Get Info's size on disk.
7. Run First Aid if nothing else explains it.

If deleting files on your Mac's own disk is what freed nothing, the post on deleted files that don't free space covers the internal disk's causes, which overlap with these.

A worked example

Say a 1 TB APFS drive shows 820 GB used, while the visible folders add up to 300 GB. The Trash is empty. In Disk Utility, the container's bar shows a second volume named Backups using 480 GB, made when the drive was chosen for Time Machine.

The files aren't missing; the backups are using the space. The owner wants the drive for files only. They make sure another backup exists, remove the drive in Time Machine settings, then delete the Backups volume. The 480 GB returns to the shared free space, with no copying.

Mistakes to avoid

• Ejecting before emptying the Trash. The deleted files stay on the drive, out of sight.
• Deleting volumes you don't recognize. It erases them permanently; mount them and look first.
• Deleting .Spotlight-V100 or .Trashes folders whole. Use Spotlight's Search Privacy and Finder's Empty Trash instead.
• Erasing the drive to "reset" it. It works, but it erases everything; try the steps above first.
• Pasting commands from forums. They delete without the Trash, and can't be undone.

How the app does it

Wombit shows what's using your storage, explains every item in plain language, and clears it safely: Trash first, undoable and logged. Its scan covers the whole disk or any folder, reading only names, sizes and dates, and file names and paths never leave your Mac.

Folders macOS didn't let it read are listed, not skipped, so you know when a total is incomplete. Hard links and APFS clones count once, the way macOS counts space.

The catalog entries for the Trash, the Spotlight index and document versions match those folders at the top of other disks as well as on your Mac:

• ~/.Trash

  Trash

  Items you've moved to the Trash. They still use space until the Trash is emptied.

  Review first · Explained only: the app shows you how

• /System/Volumes/Data/.Spotlight-V100

  Spotlight index

  The index Spotlight keeps for each disk so it can find files, and what's inside them, quickly.

  Managed by macOS · Explained only: the app shows you how

• /System/Volumes/Data/.DocumentRevisions-V100

  Document versions

  Earlier versions of documents that apps like Pages, TextEdit and Preview save as you work, so you can go back to them.

  Managed by macOS · Explained only: the app shows you how

• Time Machine local snapshots

  Hourly snapshots of your startup disk that Time Machine keeps on the disk itself, so you can restore files even without your backup disk.

  Managed by macOS · Runs tmutil for Time Machine's own snapshots, through the helper

• The Trash is Review first: it may hold the only copy of something. The app empties only your own Trash, and only when you ask, after a confirmation that says how much it will erase.
• The Spotlight index, document versions and local snapshots are Managed by macOS: explained, handled through macOS's own mechanism, never moved.

The analyzer, the map, the explanations, Undo, Put Back and Empty Trash are free. Cleanup and removing Time Machine snapshots are PRO: one payment of $4.99 with lifetime access. Every Pro tool's review is free to open, so you see what would go and why before you buy.