How do I prepare my hard drive for resale?

Selling an old hard drive? You’ll want to take a few steps to prepare it for your buyer. Following proper hard drive sanitization procedures ensures your data is protected while also providing a smooth experience for the next owner.

Why Do I Need to Prepare My Hard Drive Before Reselling It?

When you decide to sell or donate your old hard drive, you want to make absolutely certain no personal data remains on it. This protects you from identity theft if your drive ends up in the wrong hands. It also provides peace of mind knowing your private information won’t be seen. Just as importantly, preparing the hard drive for sale shows your buyer that you take data security seriously.

Failing to properly wipe a hard drive gives the buyer access to things like:

  • Emails
  • Financial statements
  • Legal documents
  • Family photos
  • Browser history
  • Saved passwords

For ethical and legal reasons, you want to avoid exposing sensitive material whenever you pass along hardware to someone else. Doing so can make you liable if they misuse your confidential data.

How Do I Remove Data from a Hard Drive?

You have a couple options for wiping your hard drive before selling it:

1. Format the Hard Drive

Formatting the drive erases all existing data. It resets everything to factory settings, leaving you with a blank slate. Here’s how to format a hard drive:

  1. On Windows, hit Start and search for “Disk Management.” On Mac, search for Disk Utility.
  2. Locate the hard drive you want to format and right-click it.
  3. Select “Format” from the right-click menu.
  4. Choose a file system (often NTFS or exFAT).
  5. Give the drive a name under “Volume Label” if desired.
  6. Check “Quick Format” to format faster.
  7. Click “Start” or “Erase.”
  8. Allow the format process to finish. This can take a couple hours for a large drive.

Formatting completely erases all user data. However, it may still leave traces of recoverable data behind. For maximum protection, you also want to…

2. Wipe the Hard Drive

Wiping goes beyond formatting to actively overwrite all data on the drive. This replaces your original bits and bytes with new meaningless data.

On Windows, use the free Secure Erase tool. On Mac, you can wipe the drive from Disk Utility:

  1. Select your hard drive and click “Erase” in Disk Utility.
  2. Choose “Most Secure 3-Pass Erase” from the drop-down.
  3. Click “Erase.” This overwrites all data with zeroes in 3+ passes.

Wiping the hard drive removes all recoverable traces of your personal data. It leaves the drive in a near-new state for the next user.

Should I Physically Destroy the Hard Drive?

For maximum data protection, you can physically destroy the hard drive. However, this is rarely necessary for consumer drives. Wiping the drive is usually good enough for safe reselling.

Destroying the hard driveplatters will guarantee no data recovery. But it also permanently destroys the hardware so it can’t be reused.

To physically destroy a hard drive:

  1. Remove the outer casing and expose the internal platters.
  2. Use a hammer to damage the platters and warp their shape.
  3. Drill holes through the platters to severely damage them.
  4. Vecro plates together to shred them apart.
  5. Degauss platters to erase magnetic data.
  6. Melt platters in a furnace to destroy completely.

This level of destruction is overkill for most home users. Wiping the drive is sufficient preparation for selling or donating a functional used hard drive.

How Do I Securely Wipe a Solid State Drive (SSD)?

Solid state drives (SSDs) store data differently than traditional hard drives. Their memory chips don’t store magnetic traces that a wipe can overwrite. So how do you securely erase an SSD?

To sanitize an SSD for resale, use one of these methods:

  • Format Tool: Use the SSD maker’s secure erase tool or formatting software. For example, Samsung Magician for Samsung SSDs.
  • Encryption: Encrypt the SSD before formatting to add protection.
  • ATA Secure Erase: Perform a firmware-level secure erase command supported by most SSDs.
  • Destroy Data Chips: If selling the SSD as-is isn’t important, physically wreck the flash memory chips.

The formatting tools for major consumer SSD brands provide adequate security for home use. Encryption and hardware destruction offer extra protection when selling SSDs.

How Do I Remove Personal Data from a MacBook or Mac?

Selling an old Mac? You’ll want to fully wipe the computer and drive to avoid exposing personal info. Here’s how to erase a Mac:

  1. Backup your files externally, such as to iCloud or an external hard drive.
  2. Sign out of iCloud and disabled “Find My Mac.”
  3. Boot into Recovery Mode by holding Command+R on restart.
  4. Select Disk Utility and click “Erase” on the startup disk.
  5. Choose a 1-pass wipe, then click “Erase.”
  6. Quit Disk Utility, then select “Reinstall macOS” to do a clean install.
  7. Follow the prompts to install a fresh OS. Skip migrating old data.

For maximum protection, encrypt your Mac’s disk before wiping. You’ll need the firmware password to decrypt it later.

Erasing the startup disk removes all your data from a Mac. It leaves the computer like new for the next owner.

Is It Safe to Sell an Old External Hard Drive?

Used external hard drives come with the same data security concerns as internal drives. An external drive contains all the same kinds of personal files and identifiers.

To prepare an external drive for sale or donation:

  1. Backup any files you want to keep elsewhere.
  2. Use the drive maker’s erase tools, or format the drive.
  3. For platters, use wipe software like Parted Magic to overwrite data.
  4. For SSDs, use the maker’s secure erase tool or encryption.

Booting from a Parted Magic CD will let you securely erase any drive. Follow the steps above to wipe an external drive before passing it along.

What Tools Should I Use to Wipe a Hard Drive?

You have a few options for erasing your old hard drives before selling or gifting them.

Here are some top free wiping tools:

Software Compatible OS
Secure Erase Windows
DiskPart Clean Windows
Parted Magic Any (Bootable)
DBAN Any (Bootable)
KillDisk Any (Bootable)
Roadkil’s Raw Write Windows
Disk Utility Secure Erase Mac

The simplest options are the native Windows and Mac tools. But bootable erasers like Parted Magic offer maximum control for wiping any drive.

Should I Remove the Hard Drive from the Computer Before Selling?

To protect your data when selling a computer, you should wipe or remove the hard drive:

  • Wipe the drive: For convenience, do a full system wipe to erase the contents.
  • Remove drive: For total security, take out the hard drive before selling the system.

If you wipe the drive, make sure you use a secure wiping tool. Quick formats don’t cut it. For people buying computers secondhand, a wiped drive is usually sufficient.

Those with highly sensitive data may want to physically remove and keep the drive instead. This guarantees no chance of recovery.


Preparing your used hard drive for sale only takes a few simple steps:

  1. Backup your files.
  2. Use disk wiping software to overwrite the drive.
  3. On Macs, erase the startup disk.
  4. Remove drives if you want total security.

Taking the time to sanitize your old drives protects your personal data. It also shows your buyer that you take security seriously. Wiping your drive helps facilitate a smooth sale or donation every time.