To make Parallels reclaim disk space, shut the virtual machine down, open its configuration and click Reclaim on the General tab, or choose File › Free Up Disk Space. Parallels then compacts the machine's disk and removes files it no longer needs. If the machine has snapshots, it can't compact the disk until you delete them.
UTM and VirtualBox work differently. UTM has Reclaim Space and Compress buttons for drives of its QEMU machines, while VirtualBox has no button for it at all. VMware Fusion has Clean Up Virtual Machine, which returns space only from Windows machines.
The reason all of them need such a step is the same. A virtual disk grows as the system inside writes to it, and it doesn't shrink when you delete files in there. Snapshots then keep older versions of the disk on top.
This post goes through each app: where it keeps its machines, what its own tools reclaim, how snapshots hold space, and what's safe to remove. If your space goes to containers instead, the posts on OrbStack and on Colima and Podman cover those tools.
Why virtual machines take so much space on a Mac
A virtual machine is a whole computer stored as files: an operating system, its apps, their updates and whatever you keep inside it. On your Mac, almost all of that is one or two large disk files inside a package or folder.
Where does each app keep its virtual machines?
| App | Default location | What one machine looks like |
|---|---|---|
| Parallels Desktop | ~/Parallels | A .pvm package, or .macvm for macOS machines |
| Parallels, App Store edition | ~/Library/Group Containers/4C6364ACXT.com.parallels.desktop.appstore/Shared/Parallels | The same packages |
| UTM | ~/Library/Containers/com.utmapp.UTM/Data/Documents | A .utm package |
| VirtualBox | ~/VirtualBox VMs | A folder with a .vbox file and its disks |
| VMware Fusion | ~/Virtual Machines.localized | A .vmwarevm package |
Machines can also live elsewhere, on an external drive or in a folder you chose. Each app can show you where: Parallels' Control Center and UTM both have a Show in Finder or Reveal in Finder action, and VirtualBox's machine list does too.
Why does a virtual disk grow but never shrink?
Most virtual disks start small and grow as the system inside writes data. Parallels says a machine takes as much space as the data inside it, and VirtualBox calls such disks dynamically allocated. A disk set to 128 GB might take only 20 GB on your Mac after a fresh install.
The growth goes one way. Parallels' documentation says it plainly: the space a machine takes expands as you add data but isn't reduced when you delete it. Delete 30 GB of files inside Windows, and your Mac sees no difference until something reclaims that space.
That's what the reclaim, compact and clean-up tools are for. They find the blocks the guest system no longer uses and give them back to your Mac.
Why does Finder show two sizes for a virtual disk?
Some virtual disks are sparse files. Apple's documentation for APFS, the Mac's file system, explains that blocks of a sparse file are stored only when something is written to them. Disk images with large empty stretches take far less space than their size suggests.
UTM's raw disk images are sparse files on APFS, so a 64 GB drive with 15 GB written takes about 15 GB. Select the file and choose File › Get Info: the Size line shows the file's size and, in parentheses, the space it takes on disk. The second number is the one that counts.
Which Storage settings category counts them?
Machines in your home folder, such as Parallels', VirtualBox's and VMware Fusion's, usually count under Documents in System Settings › General › Storage. UTM's machines sit inside its container in your Library folder, so they usually count toward System Data.
Either way, Storage settings shows one total, not which machine or snapshot holds the space. The apps' own windows and Finder are where you find that out. The steps here work the same on macOS 27 and macOS 26.
How much space is normal?
It depends on the system inside. A small Linux server can take a few gigabytes, while a Windows machine with Office and a few years of updates can take far more.
- Disk size Windows 11 asks for64 GB
- Virtual machines and container disks, typical10–150 GB · Review first
The first figure is Microsoft's minimum storage for Windows 11; a growing virtual disk of that size takes only what Windows has written. The typical range is for Macs that use virtual machines or container tools, from the research behind the app's catalog. Many Macs have less.
Snapshots, suspended states and copies of the same machine come on top of that. They're the part people most often forget, and the next sections show where each app keeps them.
Parallels: reclaim disk space with its own tools
Parallels Desktop has three tools for giving space back to your Mac: the Reclaim button, the Free Up Disk Space wizard and TRIM. They're described in its user guide for version 27, and they all work on the machine's disk from the outside.
How do you reclaim disk space in Parallels Desktop?
- Shut down the virtual machine. Suspending it isn't enough.
- Open Parallels' Control Center from the Parallels icon in the menu bar or the Dock.
- Control-click the machine and choose Configure, or select it and choose Actions › Configure.
- Click General. Next to Total size, click Reclaim.
Parallels compacts the machine's disks and removes files it no longer needs. How long it takes depends on the size of the disk and how much there is to reclaim.
On the same tab, Reclaim disk space on shutdown does this automatically each time you shut the machine down. That suits a machine whose contents change a lot, such as one you test installers in.
What does the Free Up Disk Space wizard remove?
With the machine shut down, choose File › Free Up Disk Space. The wizard shows whether you can reclaim space by removing snapshots, cache files and files the machine has piled up over time, such as statistics, memory dumps and crash dumps.
It also compacts the disks, like Reclaim. The difference is that it shows you what it found first, including snapshots, so it's a good place to start when you don't know where the space went.
Should you turn on TRIM?
TRIM lets the system inside the machine tell Parallels which blocks it no longer uses, so Parallels can reduce the disk's size as you go instead of waiting for a reclaim. To turn it on, choose Actions › Configure › Hardware, click Hard Disk, open Advanced and select Enable TRIM.
Parallels notes that the option may affect performance on hard disk drives, but not on SSDs. Every Mac that runs current versions of macOS has an SSD inside, so for a machine on your internal disk, that caveat doesn't apply.
Why doesn't Reclaim free any space?
The most common reason is snapshots. Parallels' documentation says that a machine with one or more snapshots can't have its disk compressed or resized. Delete snapshots you don't need first, then reclaim.
The second reason is that the space isn't free inside the machine. Reclaim gives back only what the system inside has already deleted, so clear what you don't need in Windows or Linux first, with its own tools, then shut down and reclaim.
The third is that the space is somewhere else: in another machine, in a copy you made, or in an installer you downloaded. The table above, and the disk map of a storage tool, show which package is large.
How do you remove a Parallels virtual machine?
- Shut down the machine, then open Control Center.
- Control-click the machine and choose Remove.
- Choose Keep files to take it off the list only, or Move to Trash to remove it.
With Move to Trash, the machine and everything inside it go to the Trash, and Parallels warns that you may not be able to restore it afterwards. Copy out anything you need from the machine before you remove it.
Snapshots: the space you don't see
A snapshot saves a machine's state so you can go back to it. It's one of the most useful features of a virtual machine, and one of the least visible uses of space.
How do snapshots hold space?
A snapshot isn't a copy of the whole machine. VMware's documentation puts it plainly: a snapshot isn't a backup. VirtualBox explains the mechanism: when you take a snapshot, it starts a new file that records only the changes made after it.
So a snapshot costs little on the day you take it, and more each day after. Every block the machine changes is kept twice, once as it was and once as it is. A snapshot taken before a large Windows update holds the whole pre-update system for as long as it exists.
Snapshots also block reclaiming in Parallels, as above. On a machine with a long list of snapshots, they're often the largest single use of space.
What is Parallels SmartGuard?
SmartGuard takes snapshots for you on a schedule. You set it up in the machine's configuration under Backup: select SmartGuard, click Details, and either choose Optimize for Time Machine or set the frequency and the number of snapshots to keep yourself.
Optimize for Time Machine takes a snapshot every 48 hours and keeps three. With your own settings, Snapshots to Keep goes up to 100, and Parallels deletes the oldest when it needs room for a new one. The number you choose there is the one that decides how much space SmartGuard can hold.
SmartGuard isn't available for macOS virtual machines, or while a machine runs in Rollback Mode.
How do you delete snapshots in each app?
| App | Where snapshots are | How to delete one |
|---|---|---|
| Parallels Desktop | Control Center, the snapshots icon, or Manage Snapshots | Select it and click Delete |
| VirtualBox | Select the machine, then Snapshots in its tools | Select it and click Delete in the toolbar |
| VMware Fusion | Virtual Machine › Snapshots | Select it and click Delete, then confirm |
| UTM | Not described in UTM's documentation | Not applicable |
Deleting a snapshot doesn't change the machine's current state. What it removes is the point you could go back to.
Why does deleting a snapshot take so long?
Because the changes it recorded have to be merged into the disk around it. Parallels says that deleting an intermediate snapshot merges its information into the next one. VMware Fusion warns that consolidating after a large change, such as a service pack, can take up to a few hours.
VirtualBox adds a caution that matters on a full disk: deleting a snapshot may need large temporary files while it works. If your Mac is nearly out of space, free some elsewhere first, so the merge has room to finish.
Which snapshots should you keep?
Keep the most recent snapshot you'd really go back to, such as the one taken before your last risky change. Older snapshots for the same reason have usually done their job once the change has proved itself.
A snapshot of a clean install is worth keeping only if you really restore to it. Many people never do, and it holds a full copy of every block that has changed since.
UTM: QEMU drives and Apple virtualization
UTM runs machines with one of two engines. QEMU can virtualize or emulate other architectures; Apple's Virtualization framework runs Linux machines, and macOS machines on Apple silicon. Their drives behave a little differently, and so do the space tools.
Where are UTM's virtual machines?
By default, inside UTM's own container: ~/. In Finder, that container shows up as a folder named UTM inside ~/, not under its bundle ID.
The easiest way to find a machine is to Control-click it in UTM's list and choose Reveal in Finder. Each machine is a .utm package that holds its settings and drives.
What do Reclaim Space and Compress do?
For QEMU machines, UTM's drive settings on macOS offer Reclaim Space, Compress and Resize. Shut the machine down, open its settings, select the drive, and choose the option you want.
- Reclaim Space rewrites the drive image as QCOW2 without the zeroed blocks, which frees them on your Mac.
- Compress does the same and also compresses the data. New data written later isn't compressed.
- Resize makes a drive larger. It takes no space on your Mac until the system inside fills it.
UTM marks all three as experimental and says to back up the machine first. Using any of them on a raw image converts it to QCOW2. For the best result, the system inside should support TRIM, so the blocks it deletes are marked as free.
How do drives of Apple virtualization machines use space?
When UTM creates a drive for a machine using Apple's Virtualization framework, it makes a raw image inside the .utm package. On an APFS disk, that image is a sparse file, so blocks that hold only zeros take no space.
On macOS 26 and later, UTM can also use Apple Sparse Image Format for these drives. UTM's documentation says the format performs better and is more efficient, but a machine that uses it can't run on an older version of macOS.
What is disposable mode?
For QEMU machines, UTM can run a machine without saving changes: Control-click it and choose Run without saving changes. Anything written to its drives is lost when it shuts down.
That makes it a clean way to try something risky without the machine growing. It isn't available for machines that use Apple's Virtualization framework.
How do you remove a UTM virtual machine?
Control-click the machine in UTM's list and choose Remove. If the machine is stored in UTM's default folder and you haven't moved it, UTM deletes its data as well, not just the entry in the list.
Copy out anything you need first. If you moved a machine elsewhere with UTM's Move action, check that folder after removing it, since UTM's documentation doesn't say what happens to data stored outside its default folder.
VirtualBox: dynamically allocated disks
VirtualBox runs on Apple silicon Macs as well as Intel ones. On Apple silicon, it runs machines with Arm systems, such as Windows 11 for Arm and Arm Linux distributions.
Fixed-size or dynamically allocated?
When you create a disk, VirtualBox offers Pre-Allocate Full Size. Selected, it makes a fixed-size file that takes the disk's full capacity at once. Not selected, the disk is dynamically allocated: it starts small and grows whenever the system inside writes to a part of the disk for the first time.
VirtualBox says the fixed-size format is slightly faster, but the dynamic one is what most people use. Its catch is the one every growing disk has: it doesn't shrink when you delete files inside.
Where does VirtualBox keep a machine's files?
Each machine has its own folder in ~/, with a .vbox settings file and its disk images. A Logs folder appears once the machine has run, and a Snapshots folder appears once you take a snapshot.
To see every disk VirtualBox knows about, with its location and the machine it belongs to, click Media in VirtualBox Manager. That's the Virtual Media Manager, and it's also the place to remove a disk image: select it, remove it, and choose to delete the file too.
Can you compact a VirtualBox disk on a Mac?
Not from VirtualBox's windows. Its documentation describes compacting a dynamically allocated disk only as a command-line step, and the system inside must first fill its free space with zeros, using a tool made for that.
If a machine's disk has grown far beyond what it holds, there are two other routes. Delete snapshots, which VirtualBox says frees disk space. Or create a new machine, move what you need into it, and remove the old one.
How do you remove a VirtualBox machine and its files?
- Shut the machine down. Remove is unavailable while it runs.
- In VirtualBox Manager, Control-click the machine and choose Remove.
- In the dialog, choose to remove the files too, not only the machine's entry in the list.
Removing only the entry leaves the folder and its disks in ~/. That's useful if you mean to add the machine again later, and a common source of forgotten gigabytes if you don't.
VMware Fusion: Clean Up Virtual Machine and AutoProtect
VMware Fusion Pro keeps each machine as a .vmwarevm package. It has its own clean-up tool and an automatic snapshot feature, AutoProtect, that's worth checking.
What does Clean Up Virtual Machine do?
Fusion's clean-up compacts and defragments a machine, and consolidates snapshot files left behind when deleting a snapshot failed. Broadcom's documentation is clear about its limit: only Windows virtual machines return freed space to your Mac.
- Shut down the machine. Clean-up doesn't run while it's on or suspended.
- Choose Window › Virtual Machine Library, select the machine and click Settings.
- Under System Settings, click General.
- Click Clean Up Virtual Machine, or select Clean up disks after shutting down virtual machine to do it every time.
The button appears only when there's something to clean up. Clean-up isn't supported for preallocated disks, or for virtual disks formatted as FAT32, FAT or exFAT.
How much space can AutoProtect hold?
AutoProtect takes snapshots for you, every 30 minutes, every hour or every day. You choose how many to keep, and Fusion deletes the oldest when it reaches that number. Each machine can have up to 100 snapshots in all.
The settings panel shows an estimate of the minimum space AutoProtect snapshots will take. Fusion's documentation warns the real figure can be much higher, depending on how much changes between snapshots. To check it, choose Virtual Machine › Snapshots and click AutoProtect Settings.
How do you delete a VMware Fusion machine?
Choose Window › Virtual Machine Library, select a machine that's shut down, and choose Edit › Delete. Then click Move to Trash. The machine, its snapshots and everything stored in it go to the Trash, where they still take space until you empty it.
Old and forgotten machines
Some of the largest virtual machines on a Mac aren't the ones in use. They came along in a migration, were made for one test, or belong to a tool you stopped using.
Intel virtual machines on an Apple silicon Mac
If you moved to an Apple silicon Mac with Migration Assistant, your old Intel machines probably came with you. Many of them can't run there in the usual way.
VirtualBox doesn't support Intel systems on an Arm host at all. Parallels Desktop, from version 20.2.0, can run some Intel machines on Apple silicon in its Pro, Business and Enterprise editions. It calls this an early technology preview and warns of very slow speeds, one processor core and missing features.
So an Intel machine on an Apple silicon Mac is often worth keeping only long enough to copy out its data. After that, its space is better used for an Arm machine you can really run.
Vagrant boxes and Tart images
Vagrant downloads a base image, called a box, the first time a project uses it, and keeps every version it downloads in ~/. The machines it creates are stored by their provider, such as VirtualBox or VMware Fusion, so they show up in those apps too.
Tart, a command-line tool for macOS and Linux machines on Apple silicon, keeps its machines in ~/ and the images it pulls in ~/. Its FAQ says it removes the least recently used cached images and macOS restore images by itself when it needs room for a new pull or clone.
Neither tool has an app window for this. Vagrant has its own command for removing old box versions, and Tart has its own for removing machines.
Container tools are virtual machines too
Docker Desktop, OrbStack, Colima and Podman each run a Linux virtual machine to host your containers. Their disks follow the same rules: they grow as images and volumes pile up, and each tool has its own way to give space back.
The OrbStack post explains why its disk file reports 8 TB, and the Colima and Podman post covers those tools' machines and caches.
Installer images you've already used
Creating a machine usually starts with a large download: a Windows or Linux ISO image, or a macOS restore image. Once the system is installed, the machine no longer needs it.
These files are usually in your Downloads folder. The App Store edition of Parallels saves machines from its Free Systems list there too, so check that folder for both.
Moving, backing up and copying virtual machines
Sometimes the best answer isn't to delete a machine but to put it somewhere else. Each app has its own way to do that safely.
Can you move virtual machines to an external drive?
Yes, through each app. Parallels sets where new machines go in its Preferences, under General, with Virtual Machines Folder; existing machines stay where they are. UTM's Move action moves a machine to another folder, such as one on an external drive.
VirtualBox's Move action, in the machine's menu, moves a machine and updates its settings to match. Moving a disk image by hand in Finder breaks VirtualBox's record of where it is, so use the app.
Use an APFS-formatted drive. Apple's APFS documentation notes that file systems without sparse-file support store every block, so a sparse disk copied to such a drive can take its full size.
Should Time Machine back up your virtual machines?
Parallels' documentation says Time Machine backs up a machine with your other files by default. A machine changes constantly while it runs, so each backup can copy a large disk file again.
To leave a machine out, open System Settings › General › Time Machine, click Options, click the add button and choose the machine's package, then click Done. Apple notes that excluded items still appear in Time Machine's local snapshots.
If you exclude a machine, back it up another way. Parallels' Optimize for Time Machine setting, covered above, is its suggested middle ground.
What happens when you duplicate a machine?
On an APFS disk, duplicating a file in Finder can make a clone, which Apple describes as a copy that takes no extra space on disk at first. The two copies share their unchanged blocks until one of them changes.
That has a surprising result. Delete one of two cloned machines and you may free much less than its size, because most of its blocks are still used by the other. A storage tool that counts clones once shows the real cost.
What's safe to remove: a decision table
Every virtual machine holds a system and data you may want, so none of them is a cache. The question is what each item costs you if it goes.
What does removing each item cost?
| Item | What you lose | Better first step |
|---|---|---|
| Free space inside a machine | Nothing | Reclaim, Compress or Clean Up in the app |
| An old snapshot | The point you could go back to | Delete it in the app's snapshot list |
| An installer image you've used | A download, if you need it again | Move it to the Trash in Finder |
| An Intel machine you can't run | Its system and anything inside | Copy out your files, then remove it |
| A machine you no longer use | Its system and anything inside | Copy out your files, then remove it in the app |
Mistakes to avoid
- Moving a disk file out of a machine's package in Finder. The machine won't start, and the app may lose track of it.
- Deleting snapshot files from a package by hand. Use the app's snapshot list, which merges what the remaining snapshots need.
- Expecting space back right after deleting files inside Windows or Linux. It comes back only after a reclaim, a clean-up or TRIM.
- Choosing Keep files or removing only the list entry, then forgetting the folder. The disks stay where they were.
- Running a reclaim on a nearly full Mac without a backup. UTM calls its tools experimental, and snapshot merges need room to work.
- Pasting cleanup commands from a web page. Commands that delete files skip the Trash, so a wrong path can't be put back.
Will reclaiming space make your Mac faster?
No. It frees space on your Mac and nothing else. The machine itself doesn't run faster because its disk file is smaller.
Space is what you get back, and on a nearly full Mac, that matters: macOS needs room for updates, and a virtual machine needs room to grow while it runs.
How do you keep virtual machines from growing back?
- Turn on Reclaim disk space on shutdown and Enable TRIM in Parallels, or the clean-up option after shutdown in VMware Fusion.
- Set a small number of snapshots to keep in SmartGuard or AutoProtect.
- Take manual snapshots for a reason, and delete them once the reason has passed.
- Use UTM's disposable mode for one-off tests on QEMU machines.
- Remove installer images once a machine is set up.
- Keep machines you rarely use on an external APFS drive.
How the app does it
Wombit finds virtual machines from Parallels, UTM, VirtualBox and VMware Fusion, along with Tart's machines and cache and Vagrant's boxes, and explains each one from the catalog's entry. Hard links and APFS clones count once. It reads only names, sizes and dates, and file names and paths never leave your Mac.
The machines are Review first, because each holds a whole system and whatever you kept in it. The app explains them with each app's own steps, as above, and leaves removing them to Parallels, UTM, VirtualBox and VMware Fusion. Tart's machines are left to Tart, and Tart's cache waits for your choice before it goes to the Trash.
Vagrant's boxes are Usually safe. If you check them in Cleanup, the app runs Vagrant's own command after the review sheet. It removes only older versions, so the item's size is the most it can free. What a command removes can't be put back, and the sheet says so.
What the app runs, after you review itPRO
- vagrant box prune --force --keep-active-boxes
- Older versions of each Vagrant box; the newest version of every box, and boxes a machine still uses, stay
~/
Parallels/ *.{pvm,macvm} Parallels Desktop virtual machines
Virtual machines you created in Parallels Desktop, each stored as one package with its disks and settings.
Review first · Explained only: the app shows you how
~/
Library/ Containers/ com.utmapp.UTM/ Data/ Documents/ *.utm Virtual machines you created in UTM, each stored as a .utm package with its disks and settings.
Review first · Explained only: the app shows you how
~/
VirtualBox VMs/ * Virtual machines created in VirtualBox, one folder per machine with its settings file and virtual disks.
Review first · Explained only: the app shows you how
~/
{Virtual Machines,Virtual Machines.localized}/ *.vmwarevm VMware Fusion virtual machines
Virtual machines created in VMware Fusion, each stored as a .vmwarevm package with its disks and settings.
Review first · Explained only: the app shows you how
~/
.vagrant.d/ boxes Base images Vagrant has downloaded to create virtual machines, including older versions of each box.
Usually safe · Runs vagrant box prune --force --keep-active-boxes
Seeing all of this is free. Cleanup is 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.
Frequently asked questions
Why is my Parallels virtual machine so big?
It holds a whole system, its apps and its updates, plus any snapshots you or SmartGuard have taken. Its disk grows as Windows or Linux writes data and doesn't shrink when files are deleted inside. Check Total size on the General tab of its configuration, delete snapshots you don't need, then click Reclaim.
Does deleting files inside Windows free space on my Mac?
Not by itself. The virtual disk keeps that space until something gives it back: Parallels' Reclaim or TRIM, UTM's Reclaim Space, or VMware Fusion's clean-up for Windows machines. Shut the machine down and use its app's tool to get the space back.
Can I delete a .pvm file in Finder?
Yes, moving a .pvm package to the Trash removes the machine and everything inside it. Removing it in Parallels' Control Center with Remove and Move to Trash does the same and keeps Parallels' list in step. Copy out the files you need first, and empty the Trash to get the space back.
Do Parallels snapshots take up space?
Yes. Each snapshot keeps the blocks that have changed since it was taken, so it grows as you use the machine. SmartGuard's settings decide how many automatic snapshots Parallels keeps, up to 100, and a machine with snapshots can't have its disk compressed until you delete them.
Is it safe to delete old virtual machines?
Only once you've copied out what you need. A virtual machine isn't a cache: it holds a system, apps and any files you saved inside it, and none of it comes back once the Trash is emptied. Remove it in its own app, so the app's list stays correct.
Why does Finder show a virtual disk as bigger than it is?
Many virtual disks are sparse files on APFS, where blocks that were never written take no space. Get Info shows the file's full size and, in parentheses, the space it takes on disk. The second number is what counts toward your Mac's storage.
Does Time Machine back up Parallels virtual machines?
By default, yes, with your other files, according to Parallels. A running machine changes constantly, so each backup can copy its large disk file again. You can exclude the machine in Time Machine's Options in System Settings, but then back it up another way.
Can I run an old Intel virtual machine on an Apple silicon Mac?
Sometimes. Parallels Desktop 20.2.0 and later can run some Intel machines on Apple silicon in its Pro, Business and Enterprise editions, as an early technology preview that's very slow and limited to one processor core. VirtualBox doesn't support Intel systems on an Arm Mac at all.
Sources
- About Apple File System · Apple
- Freeing Up Disk Space · Parallels
- Saving Snapshots of a Virtual Machine · Parallels
- Resize and Compress · UTM
- Virtual Storage, Oracle VirtualBox User Guide 7.2 · Oracle
- Clean up a Virtual Machine · Broadcom