Mac storage basics · Erasing, encryption and selling a Mac

How do I encrypt an external drive on a Mac?

Short answer: Right-click the drive in Finder and choose Encrypt, or erase it as APFS (Encrypted) in Disk Utility. You'll need the password whenever it's connected, so don't lose it.

Two ways:

  • Without erasing (APFS or Mac OS Extended drives): right-click the drive in Finder and choose Encrypt, then set a password and hint. Encryption runs in the background.
  • When formatting: in Disk Utility's Erase, choose APFS (Encrypted).

An encrypted drive asks for its password when connected (your Mac can remember it in the keychain). exFAT drives can't be encrypted this way. Don't lose the password — there's no way back in without it.

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