Wipe your hard drive completely before giving away or selling your computer

Before you hand over a computer to someone else, you need to erase everything on it—not just delete files or empty the trash. Deleted files can be recovered with basic software, so anyone who receives your machine could potentially access your passwords, financial records, photos, and personal documents. A proper wipe overwrites the storage space so deleted data cannot be reconstructed.

The method depends on your operating system and how much time you have. Windows and Mac both include built-in tools that work well for most people. If you want extra certainty or are disposing of a very old machine, third-party software or physical destruction are options. The whole process usually takes 1 to 8 hours depending on drive size and method.

Key Takeaways

  • Built-in tools—Windows Reset or Mac Erase—are free and sufficient for most computers being sold or donated.
  • Back up any files you want to keep before you start wiping, because the process is permanent and cannot be undone.
  • Disconnect from the internet and remove external drives before erasing to prevent accidental data loss elsewhere.
  • A full wipe on a modern drive takes 1 to 4 hours; older drives or multiple-pass methods can take 8 hours or longer.
  • If the computer will not start, you can still wipe it using a bootable USB drive or by removing and wiping the drive separately.

Back up your files before you erase anything

The erase process destroys all data on the drive. If there are files you want to keep—photos, documents, financial records—copy them to an external drive or cloud storage first. This is your only chance to recover them.

Connect an external hard drive or USB drive to your computer. Open File Explorer (Windows) or Finder (Mac), select the folders you need, and drag them to the external drive. Alternatively, use cloud storage like Google Drive, OneDrive, or Dropbox to upload important files. Wait for the upload to finish and verify the files are there before you proceed with erasing.

How to wipe a Windows computer

Windows includes a built-in reset tool that erases the drive and reinstalls the operating system. Go to Settings > System > Recovery. Click Reset this PC. You will see two options: Keep my files and Remove everything. Choose Remove everything.

Windows will ask whether you want to remove files locally or remove them and clean the drive. If you are selling or donating the computer, select Remove files and clean the drive—this overwrites the erased space so data cannot be recovered. The process will restart your computer and take 1 to 4 hours depending on drive size. Do not interrupt it or unplug the computer.

When it finishes, Windows will be reinstalled and the computer will restart to the setup screen. You can leave it there for the new owner, or if you prefer, shut it down before handing it over.

How to wipe a Mac computer

On a Mac, use the Erase feature in System Settings. Restart your computer and hold Command + R to enter Recovery Mode. When the macOS Utilities window appears, click Disk Utility.

In Disk Utility, select your main drive (usually called Macintosh HD) from the list on the left. Click the Erase button at the top. Choose a name for the drive (or leave the default), set the format to APFS (or Mac OS Extended if the Mac is older), and click Erase. This wipes the drive and takes 10 minutes to 1 hour depending on size.

After erasing, quit Disk Utility and you will return to the macOS Utilities window. You can reinstall macOS from there, or shut down the computer. If you want the new owner to set up macOS themselves, shut down without reinstalling.

What to do if your computer will not start

If the computer is broken or will not boot into Windows or macOS, you can still wipe the drive using a bootable USB drive. read a tool like DBAN (Darik's Boot Negation) or Eraser on a working computer, create a bootable USB drive following the tool's instructions, and plug it into the broken computer. Restart and boot from the USB drive (usually by pressing F12, Delete, or Esc during startup—the key varies by manufacturer). Run the wipe tool from the USB.

If you do not have access to another computer or are not comfortable with this process, you can remove the hard drive physically and wipe it on another machine, or take the computer to a local repair shop and ask them to securely erase the drive before disposal.

Third-party wiping software for extra security

If you want additional assurance that data cannot be recovered, third-party tools overwrite the drive multiple times with random data. Eraser (Windows, free) and Permanent Eraser (Mac, free) are common options. These tools take longer—sometimes 8 hours or more—because they write over the drive multiple times, but they provide a higher level of certainty.

For most people selling or donating a computer, the built-in Windows Reset or Mac Erase is sufficient. Third-party tools are useful if you handled highly sensitive information (medical records, financial data, trade secrets) and want to eliminate any theoretical possibility of recovery.

Physical destruction as a last resort

If the drive is too damaged to erase electronically, or if you want absolute certainty the data is gone, you can physically destroy the drive. Remove the hard drive from the computer (instructions vary by model—search "[your computer model] remove hard drive" for a guide). Use a drill, hammer, or angle grinder to damage the platters inside, or take the drive to an electronics recycler that offers destruction services.

Physical destruction is permanent and irreversible, so only use this method if you are certain you do not need any files on the drive. Most people do not need to go this far—a proper electronic wipe is sufficient for safe disposal.

What to do after the wipe is complete

Once the drive is erased, the computer is safe to sell, donate, or recycle. If you wiped using the built-in reset tools, the operating system is already reinstalled and ready for the new owner. If you used a third-party tool or bootable drive, you may need to reinstall Windows or macOS before handing it over—check the tool's documentation or the computer manufacturer's website for installation media.

Document what you did (take a photo of the completion screen if possible) in case questions arise later. When you hand over the computer, include any original documentation or recovery disks if you have them. The new owner will be able to set up the computer as if it were brand new.

Frequently Asked Questions

Can I just delete all my files instead of doing a full wipe?

No. Deleted files remain on the drive and can be recovered with free recovery software. A full wipe overwrites the storage space so recovery is not possible. Always use the built-in reset or erase tools, not just file deletion.

How long does it take to wipe a computer?

Built-in tools (Windows Reset, Mac Erase) usually take 1 to 4 hours for a modern drive. Older drives or third-party tools that overwrite multiple times can take 8 hours or longer. Do not interrupt the process once it starts.

Do I need to remove the battery before wiping a laptop?

No. Just make sure the laptop is plugged in so it does not run out of power during the wipe. Unplugging during the process can corrupt the drive and leave data partially recoverable.

What if I forget my password and cannot access Settings?

You can still wipe the drive using a bootable USB tool like DBAN, or by removing the drive and wiping it on another computer. You do not need to log in to use these methods.

Is it safe to donate a computer after wiping it?

Yes. After a proper wipe using the built-in tools or a third-party eraser, the drive is clean and safe. The new owner will have no access to your previous data. Reinstall the operating system or leave it at the setup screen for them to configure.