What is APFS? The Mac file system, explained

APFS, short for Apple File System, is how a Mac organizes files on a disk. Apple calls it "the default file system for Mac computers using macOS 10.13 or later" (Apple Disk Utility guide, checked October 30, 2026). If someone erased a drive on a recent Mac without picking a format, it is almost certainly APFS.

What APFS does

Apple lists its features as "strong encryption, space sharing, snapshots, fast directory sizing, and improved file system fundamentals". It is "optimized for the Flash/SSD storage used in recent Mac computers", but works on hard drives and external drives too. LaCie, a Seagate brand, says APFS "was first introduced with the release of macOS High Sierra (version 10.13)" (LaCie manual).

Containers and volumes

An APFS drive has a container, a partition that can hold several volumes. Apple: "When a single APFS container has multiple volumes, the container's free space is shared and is automatically allocated to any of the individual volumes as needed." That is why one external drive can show up as two or three volumes on a Mac. Diskferry lists every volume in the container with its name, format and size.

The four APFS variants

Disk Utility name	What it means	Diskferry
APFS	The default.	Reads it
APFS (Encrypted)	The volume is encrypted with a password.	Reads it after you enter the password
APFS (Case-sensitive)	"Homework" and "HOMEWORK" are two different folders.	Reads it; names that clash on Windows are saved under a safe name
APFS (Case-sensitive, Encrypted)	Both of the above.	Reads it after you enter the password

Variant names and the "Homework" example are Apple's.

Why Windows cannot read APFS

Windows reads FAT, exFAT and NTFS. Apple itself lists only "MS-DOS (FAT) and ExFAT" as Disk Utility formats "compatible with Windows". When we attached an APFS disk to Windows 11 in our own test on October 30, 2026, Windows listed its partition as type "Unknown", with no drive letter and no volume. What Disk Management shows

To read an APFS drive on a PC you need extra software: a driver that gives it a drive letter, or an app such as Diskferry that reads it in its own window. How to open an APFS drive on Windows

DiskferryMicrosoft Store

What APFS features mean on Windows

Snapshots are saved states of a volume, used by Time Machine on APFS backup disks. Diskferry reads the current state of a volume, not its snapshots. Time Machine on Windows
Encryption on an external drive is unlocked with its password. The internal SSD of a Mac with a T2 or Apple silicon chip is a different case and is not supported. Encrypted APFS
Compressed files: macOS can store files compressed. Diskferry decompresses them while copying and verifies the result; a file it cannot decode is reported as failed, never written as an empty file.

Questions

How do I know if my drive is APFS?

On a Mac, select the drive in Disk Utility and look at the format under its name. On Windows, Diskferry shows each volume's format (APFS or Mac OS Extended) for free, before you copy anything.

Is APFS better than HFS+?

For a Mac's own SSD, Apple made APFS the default. For a drive you want to read on Windows, neither works without extra software. APFS, HFS+, exFAT and NTFS compared

Last updated October 30, 2026. Still stuck? Support replies in person.