Mac storage basics · Erasing, encryption and selling a Mac

How do I securely wipe an external drive before giving it away?

Q: How do I securely wipe an external drive before giving it away?

For a hard drive, Disk Utility's Erase sheet has Security Options that overwrite the data. For an SSD, overwriting isn't reliable; the better approach is to have encrypted it (or erase it as APFS (Encrypted) first), then erase it again — without the key, the old data is unreadable. Copy off anything you want to keep first; this can't be undone.

Short answer: For hard drives, use Disk Utility's Erase with Security Options. For SSDs, erase as APFS (Encrypted) and then erase again, since overwriting isn't reliable on SSDs.

For a hard drive, Disk Utility's Erase sheet has Security Options that overwrite the data. For an SSD, overwriting isn't reliable; the better approach is to have encrypted it (or erase it as APFS (Encrypted) first), then erase it again — without the key, the old data is unreadable.

Copy off anything you want to keep first; this can't be undone.

Last reviewed October 1, 2026

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How do I securely wipe an external drive before giving it away?

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