How to open a BitLocker-encrypted USB drive on Mac

What the “not readable” message really means

macOS shows that message whenever it meets a disk it doesn’t recognize. For a BitLocker drive your data is fine: it is scrambled in an encryption format that Windows, and tools that understand BitLocker, can read. Don’t click Initialize or Erase – that would delete everything on the drive. Click Ignore instead.

Before you install anything, check three things: the drive is an external one (USB stick, SSD or hard drive), you have its password or its 48-digit recovery key, and it still opens on a Windows PC – that tells you the drive itself is healthy.

Your options for opening it

• macOS on its own: there is no built-in BitLocker support and no hidden setting that adds it. FileVault is Apple’s own encryption and is unrelated.
• A Windows PC or a Windows virtual machine: this works because Windows has BitLocker built in, and you can read and write. You need access to Windows, and a virtual machine needs a Windows licence.
• A free command-line tool such as anylinuxfs: open source and read-write, but for Apple silicon Macs only and used from Terminal.
• A BitLocker app for Mac: the quickest route if you only want your files. Several paid apps also let you write to the drive; Unbit is free and read-only. For a side-by-side look, see Best BitLocker for Mac.

Open the USB drive with Unbit

1. Download Unbit, drag it into your Applications folder and open it. It lives in the menu bar and needs macOS 13 or later (Apple silicon or Intel). On first launch it shows where to switch on Full Disk Access.
2. Plug in the USB drive, ideally straight into the Mac rather than through a hub. Unbit lists it under Drives; select it.
3. Enter the BitLocker password and choose Open Drive. macOS may ask for your Mac password once to approve read access.
4. Choose Show in Finder. The drive is mounted read-only, so you can browse it, open files and copy them to your Mac.
5. When you’re done, choose Eject Safely before unplugging the stick.

Want screenshots and more detail? See How to open a BitLocker drive on a Mac.

What you can and can’t do once it’s open

Unbit never writes to the drive, so you can browse folders, preview and open files, and copy them to your Mac. You can’t save changes back, delete files or add new ones. That is a deliberate trade-off: nothing can be changed or deleted by accident, and the drive stays exactly as Windows left it.

• To edit a file, copy it to your Mac first and work on the copy.
• To change what’s stored on the drive, or to change its BitLocker settings, use Windows.

More on what read-only means: Is BitLocker on Mac safe?.

If it doesn’t work

• The drive isn’t listed. Unplug it and plug it in again, use a port on the Mac itself, and refresh the list with ⌘R. Only external drives are supported.
• “Wrong password”. Check for typos and Caps Lock. If you have the recovery key, use that instead – see BitLocker recovery key on Mac.
• Access denied. Unbit needs Full Disk Access: System Settings › Privacy & Security › Full Disk Access.
• The drive opens in Finder without Unbit. Then it isn’t BitLocker-encrypted, or you picked an unencrypted partition on the same drive.
• It also fails on a Windows PC. The drive may be damaged or still being encrypted or decrypted. Let Windows finish, then try again.

If you have neither password nor recovery key

BitLocker can’t be bypassed – that is the point of encryption. Data recovery software can’t get around it either, and formatting the drive only erases it. Look for the 48-digit recovery key in the Microsoft account used on the PC that encrypted the drive, in a saved file or printout, or ask your IT administrator for a work drive.