APFS, Mac OS Extended or exFAT: formatting a drive for a Mac

APFS vs exFAT comes down to one question: will the drive ever need to work with a Windows PC, a camera or another device that isn't a Mac? If not, choose APFS. It's the Mac's own file system, the default since macOS High Sierra, and the format Time Machine, Photos, Final Cut Pro and the App Store want.

Choose exFAT only for a drive that has to move between a Mac and Windows, or between a Mac and devices that read exFAT. It works on both, but it keeps no journal, has no permissions or encryption of its own, and Time Machine and Apple's media libraries can't use it.

Mac OS Extended (Journaled) is the older Mac format. It still works, and some of Apple's apps accept it, but a new drive for a current Mac has no reason to use it.

MS-DOS (FAT) is for small drives of 32 GB or less that older devices must read, and it can't hold a single file of 4 GB or more.

Whatever you choose, erasing a drive to format it deletes everything on it. Copy anything you need somewhere else first.

The formats Disk Utility offers

Disk Utility, in your Applications folder's Utilities folder, is where macOS formats drives. Its Erase dialog asks for two things: a format, which decides how files are stored, and a scheme, which decides how the drive is divided.

Format	What Apple says it's for	Best for
APFS	The default for Macs since macOS 10.13	Any drive used only with Macs
APFS (Encrypted)	APFS with the volume encrypted	Drives that leave the house
APFS (Case-sensitive)	Treats Homework and HOMEWORK as different	Only when a tool requires it
Mac OS Extended (Journaled)	Compatibility with macOS 10.12 or earlier	Old Macs, existing drives
ExFAT	Windows volumes over 32 GB	Drives shared with Windows
MS-DOS (FAT)	Windows volumes of 32 GB or less	Small drives for older devices

APFS and its variants

Apple describes APFS as the file system for Macs with macOS 10.13 or later, with strong encryption, space sharing, snapshots and fast directory sizing. Apple's developer documentation adds clones, copies of a file that take no extra space, and sparse files, which store only the parts actually written.

There are four variants: APFS, APFS (Encrypted), APFS (Case-sensitive), and APFS (Case-sensitive, Encrypted). Apple's advice is to choose plain APFS if you don't need encryption or case sensitivity.

What is an APFS container?

APFS puts volumes inside a container, and the volumes share the container's free space. Apple's Disk Utility guide says each volume uses only what it needs, and you can set a reserve or a quota for a volume if you want limits. Each volume in a container can even use a different APFS variant.

That's why one APFS drive can hold, say, a volume for Time Machine and a volume for files, without deciding their sizes in advance. The post on Disk Utility's storage views explains how containers and volumes appear there.

What format is your Mac's own disk?

APFS, on every Mac running macOS 10.13 or later. Apple's Disk Utility guide explains that macOS is installed on a volume group: a volume named Macintosh HD for the system and Macintosh HD - Data for your files, both in one APFS container. The post on Macintosh HD and its Data volume explains why there are two.

You can't erase or reformat your startup volume from Disk Utility while the Mac is running from it; Apple's guide sends you to macOS Recovery for that. This post is about external drives.

Mac OS Extended (Journaled)

Mac OS Extended, also called HFS Plus, was the Mac's format before APFS. Earlier editions of Apple's Disk Utility guide describe four variants, all for compatibility with Macs using macOS 10.12 or earlier. The journal is what protects the file system's integrity if a write is interrupted.

Apple's Disk Utility guide for macOS 26 and 27 no longer describes Mac OS Extended among its formats. The format is still supported, though: Apple's articles for Photos and iMovie libraries still accept Mac OS Extended (Journaled) drives, and drive makers such as Seagate still give steps for choosing it in Disk Utility on macOS 26 Tahoe.

Is Mac OS Extended going away?

Partly. Apple says that in macOS 28 and later, Mac OS Extended will be supported only for volumes that aren't encrypted. Starting with macOS 26, your Mac may warn you about an encrypted Mac OS Extended drive. Unencrypted Mac OS Extended volumes stay supported.

If you have an encrypted Mac OS Extended drive, Apple's article describes three ways out: convert it to encrypted APFS, decrypt it, or back it up and erase it as APFS or APFS (Encrypted).

exFAT

ExFAT is Microsoft's format for flash drives and memory cards, and both macOS and Windows read and write it. Apple's Disk Utility guide recommends it for Windows volumes over 32 GB. It's also the format the SD Association specifies for SDXC cards, which hold more than 32 GB and up to 2 TB.

It's simple by design. Microsoft's comparison of Windows file systems lists what exFAT doesn't do: no journaling, no file owners, no permissions, no encryption of its own, no hard links. A single file can be as large as you're likely to need.

MS-DOS (FAT)

MS-DOS (FAT), FAT32 on most drives, is the oldest and most widely readable format. Apple recommends it for Windows volumes of 32 GB or less. Microsoft lists its maximum file size as 4 GiB, which rules out long videos, disk images and most AI models.

For both FAT and exFAT, Disk Utility limits the volume's name to 11 characters.

APFS vs exFAT: the differences that matter

On a spec sheet the two look like rivals. In practice they're for different jobs, and the differences show up the first time you unplug a drive in a hurry or try to point Time Machine at it.

	APFS	Mac OS Extended (Journaled)	exFAT	MS-DOS (FAT)
Windows reads and writes it	No	No	Yes	Yes
Time Machine backups	Yes, preferred	Existing backups only	No	No
Photos or iMovie library	Yes	Yes	No	No
App Store large apps	Yes	No	No	No
Built-in encryption	Yes	Yes, until macOS 28	No	No
Snapshots and clones	Yes	No	No	No
Largest single file	Very large	Very large	Very large	4 GiB

The Time Machine, Photos, iMovie and App Store rows come from Apple's own support articles; the file size and encryption rows for exFAT and FAT from Microsoft's comparison.

What happens if you unplug an exFAT drive?

ExFAT keeps no journal, so an interrupted write can leave its directory damaged. Seagate's instructions for macOS Tahoe say exFAT drives must be ejected safely to prevent corruption for exactly that reason. Always eject an exFAT drive before you pull the cable.

If one was unplugged mid-copy, run First Aid on it in Disk Utility before you trust it again. Apple says to run First Aid on each volume, then each container, then the drive itself.

Why do permissions and ownership matter?

Mac apps that keep libraries, such as Photos, depend on file permissions. Apple's Photos article tells you to select Ignore ownership on this volume if copying a library fails, and notes that the checkbox doesn't exist on a drive that isn't formatted for Mac. On exFAT, the fix simply isn't available.

That's also why Final Cut Pro's support article warns that drives pre-formatted as exFAT or FAT32 might not perform as expected, and asks for APFS.

Does APFS work on a hard disk?

Yes. Apple's Disk Utility guide says APFS is optimized for flash and SSD storage but can also be used with traditional hard disks and external drives. And APFS is Apple's preferred format for Time Machine backup disks, which are often hard disks.

Mac OS Extended (Journaled) on a hard disk is also fine if a drive already uses it. There's no need to reformat a working drive just to change format.

What about Spotlight on exFAT?

Apple's documentation doesn't say how Spotlight treats exFAT drives. What is clear is that Spotlight keeps its index in a hidden folder at the top of each disk it searches, which is one reason a drive can show less free space than its files add up to.

The post on an external drive that looks full with no files covers those hidden folders.

Which format should an encrypted drive use?

APFS (Encrypted). Apple says that in Disk Utility you must erase a drive to encrypt it this way, and that you then enter the password each time you connect it; you can change the password later with File › Change Password. Apple's guide also mentions a way to encrypt a disk without erasing it.

ExFAT has no encryption of its own, according to Microsoft's comparison, so a drive shared with Windows can't be protected by the format. And encrypted Mac OS Extended is the one variant Apple says won't be supported from macOS 28.

Can a Mac read NTFS drives?

NTFS is Windows' own format, and Disk Utility can't create it. Parallels' guide to moving virtual machines notes that macOS doesn't write to NTFS drives by default, which is why it suggests exFAT for drives shared with Windows. If a drive from a PC shows up as read-only, that's usually why.

Which format for which drive?

The right format depends less on the drive and more on what it's for and which devices will use it. Here's the short version.

Drive	Format	Scheme
External SSD used only with Macs	APFS, or APFS (Encrypted)	GUID Partition Map
Hard disk used only with Macs	APFS	GUID Partition Map
Time Machine backup disk	APFS, Time Machine sets it up	GUID Partition Map
Drive shared with Windows	ExFAT	GUID or Master Boot Record
Camera memory card	What the camera or card standard expects	Usually set by the camera
Old Mac with macOS 10.12 or earlier	Mac OS Extended (Journaled)	GUID Partition Map

An external SSD for a Mac

APFS. It's what the drive's speed and Apple's apps both expect. If the drive will travel, choose APFS (Encrypted): Apple says you then enter a password whenever you connect it, so a lost drive doesn't give away your files.

The post on freeing up space with an external drive covers what to move to it once it's formatted, from the Photos library to virtual machines.

A Time Machine disk

Let Time Machine handle it. Apple says APFS or APFS Encrypted is the preferred format for a backup disk, and if you choose a disk that isn't APFS, Time Machine offers to erase and reformat it. A disk formatted for Windows can't be used until it's erased.

Older backup disks formatted as Mac OS Extended (Journaled) or Mac OS Extended (Case-sensitive, Journaled) still work, and Time Machine doesn't ask to erase a Mac OS Extended disk that already holds a backup. The post on a Time Machine disk that's full explains how it manages space.

Can one APFS drive hold Time Machine and your files?

Yes, as two volumes. Apple says the entire APFS volume used for backups is reserved for Time Machine, so to store other files on the same physical drive, add a second APFS volume in Disk Utility. The two volumes share the drive's free space.

Keep Photos, iMovie and Final Cut Pro libraries off it, though: Apple says they can't be stored on a storage device used for Time Machine backups.

A drive shared with Windows

ExFAT, for anything over 32 GB. Seagate's instructions advise formatting such a drive on the Mac rather than on Windows, because macOS doesn't support every allocation unit size Windows can choose, and an unsupported one can stop the drive from mounting on a Mac.

For the scheme, Apple says GUID Partition Map works with all Intel and Apple silicon Macs and some newer Windows PCs, while Master Boot Record is compatible with all Windows PCs. If an older PC can't see the drive, Master Boot Record is the one to try.

A drive for your Photos library

APFS, or Mac OS Extended (Journaled) if the drive already uses it. Apple's Photos article names those two formats, and says a library can't live on a Time Machine drive, an SD card, a USB flash drive or a network drive. An exFAT drive has to be erased first.

The post on moving the Photos library to an external drive has Apple's steps and the checks that make the move safe.

A drive for local AI models

APFS. Model files are often larger than 4 GB, which rules out MS-DOS (FAT) entirely, and exFAT adds the risks of a format without a journal. The post on keeping AI models on an external drive covers each tool's folder setting and why exFAT has tripped some of them.

A camera memory card

A camera card is the camera's drive more than the Mac's. The SD Association specifies FAT32 for SDHC cards up to 32 GB and exFAT for SDXC cards above that, and it recommends its own SD Memory Card Formatter over operating systems' tools, which it says may not be optimized for SD cards.

Check your camera's manual for how it expects cards to be formatted. Copy the photos off before any format, because a card's format erases it like any drive.

A scratch or cache drive for video and photo apps

These apps write large temporary files constantly, so speed matters and the format has to be one the app supports. Adobe lists APFS and Mac OS Extended for Photoshop's scratch disks on a Mac, as the post on Photoshop's scratch disk explains.

DaVinci Resolve's cache and proxy folders can live on a fast external drive as well; the post on DaVinci Resolve's cache covers where they go. For a Mac-only drive, APFS is the simple choice for both.

Partition schemes: GUID, MBR and APM

The scheme, or partition map, describes how the whole drive is divided. Disk Utility asks for it only when you erase the drive itself, not a volume on it.

Which scheme should you choose?

Apple's guide lists three. GUID Partition Map is for all Intel and Apple silicon Macs, and some newer Windows PCs can use it. Master Boot Record is for compatibility with all Windows PCs. Apple Partition Map is for old PowerPC Macs.

For any drive used with current Macs, choose GUID Partition Map. Apple also notes that on a drive using Master Boot Record, some partitions may not be available to Time Machine.

Why doesn't Disk Utility show the Scheme menu?

Because a volume is selected instead of the drive. Apple's steps say to choose View › Show All Devices first and select the drive at the top of the hierarchy in the sidebar. Disk Utility first opens in a simpler view that lists only volumes, and some tasks, erasing a whole drive among them, need the full view.

Should you partition a drive?

Rarely, with APFS. Apple's guide says that with APFS you shouldn't partition a disk in most cases; add APFS volumes to one partition instead, so they share space. A partition still makes sense when one drive needs two different formats, such as an APFS part for your Mac and an exFAT part for a PC.

Case-sensitive formats: when to avoid them

Disk Utility offers case-sensitive versions of APFS and Mac OS Extended. They sound like a technical upgrade, but for most people they're a trap.

What does case-sensitive mean?

Apple's example: on a case-sensitive volume, folders named "Homework" and "HOMEWORK" are two different folders. On the default, case-insensitive volume, they're the same name, and you can't have both in one place. Apple's APFS documentation notes that case-insensitive is the default on macOS.

What goes wrong with a case-sensitive drive?

Copying is the first problem. Two files whose names differ only in capital letters can sit side by side on a case-sensitive drive, but not on your Mac's case-insensitive startup disk, so copying them back means one would have to replace the other.

Some software doesn't support case-sensitive volumes at all. Adobe's support site, for one, has an article about an installer error that reads "Case-sensitive drives not supported".

When is case-sensitive the right choice?

When a tool you use specifically needs it, usually for software that will run on Linux or another system where case matters. Even then, a separate case-sensitive APFS volume on the drive keeps the rest of your files on the default.

How to format a drive in Disk Utility

Formatting is erasing. Every step below deletes everything on the drive or volume you select, and there's no Undo or Trash for it.

Before you erase anything

1. Copy anything you need from the drive to another drive or your Mac, and check the copy.
2. If the drive held Time Machine backups, decide whether you still need them; erasing removes them.
3. Eject other drives you aren't formatting, so you can't select the wrong one.
4. Write down the drive's capacity, so you can recognise it in Disk Utility's sidebar.

How do you erase a drive in Disk Utility?

These are Apple's steps for macOS 27, the same as in macOS 26:

1. Open Disk Utility, from the Utilities folder in Applications.
2. Choose View › Show All Devices.
3. In the sidebar, select the drive itself, at the top of its hierarchy, not a volume under it.
4. Click Erase in the toolbar.
5. Enter a name for the volume.
6. Choose GUID Partition Map from the Scheme menu.
7. Choose a format from the Format menu, and enter a password if you chose an encrypted one.
8. Click Erase, then Done.

Can you erase a drive from Finder instead?

Yes, for a simple erase. Apple's guide says to Control-click the external drive in the Finder sidebar, choose Erase Disk, optionally rename it, choose a format, and click Erase. Use Disk Utility when you need to choose the scheme or see every volume.

What about secure erase?

Disk Utility's Security Options appear only for some drives. Apple says they aren't available for SSDs at all, and suggests encryption from the start instead, such as FileVault for a Mac's own disk. An encrypted drive's contents are unreadable without its password, which makes erasing it far less of a worry.

Can you add a volume instead of erasing?

On an APFS drive, yes. Select an existing APFS volume, click the add volume button in the toolbar, name the new volume and choose an APFS format, then click Add. The new volume shares the container's free space, and nothing on the other volumes is touched.

Deleting a volume later erases all its data, so treat that button with the same care as Erase.

Changing a drive's format later

Changing format almost always means erasing. Plan for the time it takes to copy everything off and back.

How do you check a drive's format?

Select the drive in Finder and choose File › Get Info: the format is listed under General Information. Disk Utility shows it too, under the volume's name when you select it.

Can you convert a drive to APFS without erasing it?

For Mac OS Extended, Apple documents one: select the volume in Disk Utility with View › Show Only Volumes, then choose Edit › Convert to APFS and confirm. Apple describes it for encrypted Mac OS Extended volumes, and notes that it doesn't apply to encrypted Time Machine disks.

For an exFAT or FAT drive, there's no such command in Apple's documentation. Copy the files off, erase the drive as APFS, and copy them back.

What if a drive holds snapshots you can't see?

APFS drives can hold snapshots, which keep deleted files' space in use until the snapshot goes. Time Machine and some backup apps make them. The post on APFS snapshots explains who makes them and how to see them in Disk Utility.

A worked example: one drive for a Mac and a PC

Say you have a new 2 TB SSD. You want most of it for your Mac, as APFS, but also a part you can plug into a Windows PC at work. A partition is the one case where Apple's advice against partitioning APFS drives doesn't apply, because you need two formats.

Step one: erase the drive as APFS

Copy off anything the drive came with that you want, such as the maker's software. Then, in Disk Utility, choose View › Show All Devices, select the drive itself, click Erase, choose GUID Partition Map and APFS, and name it.

Step two: add an exFAT partition

Select the APFS volume and click Partition in the toolbar. Click the add button below the pie chart, then Add Partition in the dialog that appears. Name the new partition, keeping to 11 characters, choose ExFAT from the Format menu, enter a size, and click Apply, then Partition.

Apple's guide warns to back up before creating partitions. On a new, empty drive there's nothing to lose, which is why it's the best moment to do this.

Step three: check both parts

Each partition now appears in Finder's sidebar as its own drive. The APFS part works like any Mac drive: Photos libraries, App Store large apps and APFS volumes are all possible there. The exFAT part is for files you carry between computers.

Remember the trade-off: the exFAT partition's size is fixed, and it keeps no journal. Eject the drive every time before you unplug it, from either computer.

Would a GUID scheme work on the PC?

Apple says some newer Windows PCs can use GUID Partition Map, and Master Boot Record is compatible with all of them. If the PC at work doesn't see the exFAT part, erasing the whole drive with Master Boot Record is the fallback, at the cost of starting again.

Problems and fixes

Most formatting trouble comes from a drive formatted for one job being used for another.

What you see	Likely cause	What to do
Can't copy files to a drive from a PC	It's NTFS, which macOS doesn't write to by default	Copy files off, erase it as exFAT or APFS
"File is too large" on a drive	MS-DOS (FAT) can't hold files of 4 GiB or more	Erase it as exFAT or APFS
Time Machine wants to erase the drive	It isn't APFS or an existing Mac OS Extended backup	Use a drive meant only for backups
Photos library won't copy, no Ignore ownership	The drive isn't formatted for Mac	Erase it as APFS
A Windows-formatted drive won't mount	An allocation unit size macOS doesn't support	Format it on the Mac instead
No Scheme menu in Erase	A volume is selected, not the drive	View › Show All Devices, select the drive

Why is the Erase button dimmed?

Apple's guide says a volume can't be erased while it's in use. For an external drive, quit the apps using it, close any documents open from it, and try again. For your startup disk, Apple's route is Disk Utility in macOS Recovery, and on a Mac being sold or given away, Erase Assistant.

When should you run First Aid?

When a drive was unplugged without ejecting, when files on it won't open, or when it won't mount properly. Apple says Disk Utility can fix certain problems with a drive's formatting and directory, though not all, and that a disk Disk Utility says is about to fail needs replacing, not repairing.

Is it worth reformatting a drive that works?

Only if its format is stopping you from doing something: Time Machine, a Photos library, an App Store install, or sharing with a PC. A Mac OS Extended drive that does its job can stay as it is, as long as it isn't encrypted Mac OS Extended, which Apple says won't be supported from macOS 28.

How the app does it

Wombit doesn't format drives; that stays with Disk Utility and Finder, as above. It shows what's using space on your Mac and explains every item in plain language, scanning the whole disk or any folder and reading only names, sizes and dates. File names and paths never leave your Mac.

Hard links and APFS clones count once, the way macOS counts space, so files that share storage on an APFS volume aren't counted twice. Folders macOS didn't let it read are listed, not skipped.

Items the catalog knows get a level: Safe items, which their owner recreates with nothing lost, start checked and count in the headline number, while Review first items such as libraries and large old files wait for your choice. Time Machine's local snapshots are Managed by macOS: explained and handled through macOS's own mechanism.

The analyzer, the map and the explanations are free. Cleanup and 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.