How to format a drive as ext4 from a Mac

Why Disk Utility can't do it

Disk Utility and diskutil format only what macOS has a formatter for: APFS, Mac OS Extended, ExFAT and MS-DOS (FAT). diskutil listFilesystems names no ext file system, even with an ext4 driver such as Extent installed. Extent reads and writes ext4, but it doesn't create or repair file systems.

Creating ext4 is the job of mkfs.ext4, part of e2fsprogs – the same tools Linux formats its disks with. They build on macOS too, and Homebrew has them ready.

Before you start

• Formatting erases everything on the disk. Copy what you need first, and check the disk's number twice before the commands below.
• Who will write to the disk on Linux? A new file system's top folder belongs to root, so an ordinary user can't add files there. -E root_owner=1000:1000 gives it to the first user instead – ID 1000 on Ubuntu, Debian and Raspberry Pi OS; id -u on the Linux machine says for sure.
• Is the Linux on the other end older than 5.15? e2fsprogs 1.47, which Homebrew installs, turns on the orphan file, which Linux reads from 5.15 on. For an older kernel (uname -r), add -O ^orphan_file. Extent reads and writes the disk either way.
• A system card for a Raspberry Pi needs no formatting: Raspberry Pi Imager writes the whole card, partitions and all.

Format a drive as ext4 on the Mac

In the Terminal. You need Homebrew.

1. 1

   Install e2fsprogs

   brew install e2fsprogs. Homebrew installs it “keg-only”, off the PATH, so the commands below call it by its full path.

2. 2

   Find the disk

   diskutil list shows it as, say, /dev/disk4 – external, physical, the size of your drive. Everything after this step erases that disk.

3. 3

   Give it one Linux partition

   diskutil partitionDisk /dev/disk4 MBR %Linux% %noformat% 100% creates disk4s1, of type Linux, and leaves it empty. MBR suits SD cards and drives up to 2 TB; for larger ones, see below.

4. 4

   Unmount it

   diskutil unmountDisk /dev/disk4

5. 5

   Create the ext4 file system

   sudo "$(brew --prefix e2fsprogs)/sbin/mkfs.ext4" -L DATA -E root_owner=1000:1000 /dev/rdisk4s1 – DATA is the disk's name, up to 16 characters. It asks for your password.

6. 6

   Disconnect the disk and connect it again

   macOS doesn't look at a freshly formatted disk again by itself. Plugged back in, it mounts through Extent in the Finder, read-only until you turn writing on for it.

brew install e2fsprogs
diskutil list
diskutil partitionDisk /dev/disk4 MBR %Linux% %noformat% 100%
diskutil unmountDisk /dev/disk4
sudo "$(brew --prefix e2fsprogs)/sbin/mkfs.ext4" -L DATA -E root_owner=1000:1000 /dev/rdisk4s1
diskutil eject /dev/disk4

Checked on macOS 27.0.1 with e2fsprogs 1.47.4 from Homebrew: the partition, the format, and Extent mounting the result by itself. Extent's own tests format physical USB drives with the same mkfs.ext4.

Drives over 2 TB: GPT instead

MBR stops at 2 TB, and diskutil refuses it on a larger drive. Use GPT, with the type Linux gives its data partitions:

diskutil partitionDisk /dev/disk4 GPT %0FC63DAF-8483-4772-8E79-3D69D8477DE4% %noformat% 100%
diskutil list /dev/disk4

On a large drive diskutil puts a small EFI partition first, so the Linux one is disk4s2. It also adds a 134 MB Apple_Boot partition after any partition of 1 GB or more whose type it doesn't know. Linux has no use for it; remove it with diskutil eraseVolume "Free Space" dummy disk4s3 – the identifier diskutil list shows for Apple_Boot – then unmount and format /dev/rdisk4s2 as in steps 4 and 5.

Or let Linux do it

• On a Linux computer or a Raspberry Pi: find the drive with lsblk, then sudo mkfs.ext4 -L DATA /dev/sdX1 on its partition – or use GNOME Disks.
• In a Linux virtual machine on the Mac: UTM passes a USB drive through to the virtual machine – with its QEMU backend, and on macOS 27 with Apple's too – and the same command formats it there.

Other apps that format ext4 on a Mac

Paragon extFS for Mac formats, checks and repairs ext volumes. It is a kernel extension, so on a Mac with Apple silicon it needs Reduced Security, and it costs $39.95. Every way to read and write ext4 on a Mac is compared in how to read and write ext4 on a Mac.

After formatting

• Writing from the Mac: a disk made with today's defaults – metadata checksums and their seed, 64-bit, the orphan file – is ext4 Extent writes. Writing is a one-time purchase and a switch per disk.
• Checking it: the same package has e2fsck. sudo "$(brew --prefix e2fsprogs)/sbin/e2fsck" -fn /dev/rdisk4s1 checks an unmounted disk and changes nothing.
• Extent doesn't format or repair. It mounts what mkfs.ext4 makes and tells you when a disk needs e2fsck on Linux.

Frequently asked questions