What Disk Management shows for a Mac drive
Open Disk Management with a Mac drive attached and you see something odd: a small partition Windows calls healthy, a large one it does not understand, and no drive letters. That is normal for a Mac drive, and it means Windows sees the hardware.
What we saw on Windows 11
We erased a disk on a Mac the way Disk Utility does (GUID partition map, APFS) and attached it read only to a Windows 11 PC on October 30, 2026. PowerShell and diskpart reported:
| Partition | Size | What Windows reported | What it is |
|---|---|---|---|
| 1 | 200 MB | Type "System", FAT32, healthy, hidden, no drive letter | The EFI System Partition that macOS added when it erased the disk. It holds none of your files. |
| 2 | The rest of the drive | Type "Unknown", hidden, no file system, no drive letter | The APFS container with your files. Windows cannot read it. |
Disk Management lists the same partitions; the first has the EFI System Partition type. On our smaller 256 MB test disk, made on a Mac without an EFI partition, Windows listed only "Unknown" partitions, one APFS and one HFS+.
What not to do in Disk Management
- Do not format, delete or create a new simple volume on the unknown partition. Each of these replaces your Mac files.
- Do not initialize the disk if asked; choose Cancel.
- Do not bother assigning a drive letter: Windows still cannot read what is behind it, and opening it leads to the "You need to format the disk" prompt. About that prompt
Open it instead
If Disk Management lists the disk, Diskferry can usually open it: click Find Mac drives, allow the Windows prompt, and the drive appears with its Mac volumes. The EFI partition is ignored. If the disk is missing from Disk Management altogether, the problem is the connection or the drive itself. Drive not showing up
Questions
Can I delete the EFI System Partition to get the space back?
Do not. It is part of how the Mac set up the disk, and Disk Management may refuse anyway. If you want the whole drive for Windows, copy your files off first and then erase the drive.
Why are the partitions marked hidden?
In our test Windows reported both Mac partitions as hidden, with no drive letter. That is what you should expect from a healthy Mac drive; it does not mean anything is wrong.
Last updated October 30, 2026. Still stuck? Support replies in person.
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