Wiping the hard drive on a Mac is an effective way to erase all of the data, settings, and installed apps from your Mac’s hard drive before selling, giving away or recycling your Mac. A complete wipe leaves no trace of your personal information behind and resets your Mac to factory default settings.
Why Would You Want to Wipe a Mac’s Hard Drive?
There are a few key reasons why you may want to fully erase your Mac’s hard drive:
- You’re selling or giving away your Mac – Wiping the hard drive protects your personal information from being accessed by the new owner.
- You’re experiencing performance issues – Wiping the hard drive provides a clean slate that can resolve software issues or sluggish performance.
- You’re recycling your old Mac – A wipe ensures no personal data is retrievable from the hard drive before recycling.
Additionally, wiping your hard drive is an important step if you want to install a newer version of macOS that is incompatible with your current OS. A clean install requires a blank hard drive.
How to Back Up Your Mac Before Wiping the Hard Drive
Before wiping your Mac’s hard drive, it’s critical to back up your important files, settings and data. This will allow you to restore your applications, files, settings and more after wiping the hard drive.
There are a few ways to back up a Mac:
- Time Machine – Time Machine is the built-in backup utility in macOS that allows you to back up everything on your Mac to an external hard drive or AirPort Time Capsule.
- Cloud storage – Services like iCloud, Dropbox or Google Drive allow you to back up files by uploading them to the cloud.
- External drive – Manually copying important files to an external hard drive or storage device.
- Clone drive – Use disk utility or a third party app to create a bootable clone of your entire hard drive.
Ideally, use a combination of methods to ensure you have a solid backup before wiping your Mac. For example, use Time Machine to do a full system backup to an external hard drive, and also upload important documents and files to iCloud.
How to Wipe a Mac Hard Drive
There are a couple options for securely wiping a Mac’s hard drive:
Option 1: Use Disk Utility
Disk Utility is an app included with macOS that allows you to erase and format drives. Here are the steps to use Disk Utility to wipe your startup disk:
- Restart your Mac and hold down Command + R keys on startup to boot into Recovery Mode.
- Select Disk Utility from the options presented.
- Click “View” in the top left corner and select “Show All Devices.”
- Select your startup disk in the sidebar.
- Click the “Erase” tab.
- Choose a format for the wiped drive, like “APFS.”
- Select “Scheme” > “GUID Partition Map.”
- Choose “Mac OS Extended (Journaled)” as the format.
- Click Erase. This will fully wipe your startup drive.
The Disk Utility method will securely erase your Mac’s hard drive by overwriting it with zeros. This process may take several hours depending on your hard drive size.
Option 2: Use Third Party Software
There are more advanced third party utilities available that can securely wipe your Mac’s hard drive:
- White Canyon Wipe Drive – Affordable software that Department of Defense standards to overwrite hard drive data.
- Mac Internet Security X9 – Includes a “Secure Delete” feature that overwrites data 35 times.
- BitRaser – Uses government-grade algorithms to permanently erase data on Macs and storage devices.
These types of advanced tools utilize techniques like multi-pass overwriting to meet higher security standards for hard drive wiping. They provide more options for the number of overwrite passes and data wiping patterns.
The downside is there is often a paid software license required, unlike the free Disk Utility method.
How to Securely Erase an External Hard Drive or Storage Device
A similar process can be used to securely wipe external USB hard drives, SD cards or other storage devices on a Mac:
- Connect the external storage device to your Mac.
- Open Disk Utility.
- Select the external storage device in the sidebar.
- Click Erase and configure the settings.
- Choose a name and format like “APFS.”
- Select “Mac OS Extended (Journaled)” as the format.
- Click Erase to wipe the external device.
This will completely erase all of the data on an external storage device in the same secure method used for wiping a startup disk.
How to Securely Erase Individual Files or Folders
If you just need to erase specific personal files or folders on your Mac, there are a couple options:
- Drag files/folders to the Trash, then choose Finder > Empty Trash. This will delete them from your Mac.
- Use a secure delete tool like White Canyon Destroy File to overwrite files multiple times.
- Use a file shredder like File Shredder Lite that overwrites data beyond recovery.
But keep in mind that simply deleting sensitive files normally only removes pointers to them, with the actual data still left on your hard drive. Use a secure erase tool for individual files and folders you want to wipe beyond recovery.
Tips for Erasing a Mac Hard Drive
Follow these tips for a smooth process when wiping your Mac:
- Back up your data – Use Time Machine, cloud storage and even a clone of your hard drive.
- Delete unnecessary files – Remove any old unused files to speed up the wipe process.
- Use a wired internet connection – This ensures the wiping won’t be interrupted.
- Erase in Recovery Mode – Boot into Recovery Mode before wiping to clear the startup disk.
- Stay powered – Connect your Mac to AC power so the battery doesn’t die mid-wipe.
- Allow enough time – Erasing and rewriting an entire drive can take hours depending on drive size.
Other Methods to Securely Erase a Mac Hard Drive
In addition to Disk Utility and third party wiping software, there are a couple other options for securely erasing a Mac hard drive:
Use macOS Recovery
The latest versions of macOS have an Erase feature in macOS Recovery that can format the startup drive and delete all its data. Here are the steps:
- Restart Mac and hold Command + R keys to boot into Recovery mode.
- Select Disk Utility then continue to Erase process.
- Choose Mac OS Extended (Journaled) format.
- Click Erase to wipe the startup drive.
Use Terminal
For advanced users, the Terminal app can be used to securely erase data by overwriting free disk space. Use these commands:
diskutil secureErase freespace LEVEL /Volumes/DRIVE
Replace “LEVEL” with 1-4 passes and “DRIVE” with the startup disk name. This will overwrite existing free space on the targeted drive.
How to Securely Wipe a Mac SSD
Solid state drives (SSDs) store data differently than traditional hard disk drives (HDDs). So securely erasing an SSD requires a few specific steps:
- Use Disk Utility to write zeros – Startup to Recovery Mode and overwrite free space.
- Use third-party SSD erasing software – Tools like Parted Magic have SSD erase functions.
- Enable TRIM support – TRIM tells an SSD which blocks of data are no longer in use and can be wiped.
Make sure to use disk utilities or commands specifically made for SSDs, as HDD tools are not as effective. Wiping SSDs should perform a cryptographic erase for proper sanitization.
How to Securely Erase and Reinstall macOS
After wiping your Mac’s hard drive, the final step is to reinstall macOS for a fresh copy of the operating system.
- Boot to Recovery Mode by holding Command + R on restart.
- Select “Reinstall macOS” after the startup options appear.
- Click Continue and follow the installation prompts.
- Choose your wiped hard drive as the install destination.
- Allow the OS to install then migrate data back from your backup.
This will give you a newly cleaned hard drive with a fresh macOS install. Don’t forget to restore your files, settings and applications from backups after installation.
Frequently Asked Questions
Is wiping a Mac hard drive necessary before selling it?
Yes, wiping the hard drive is highly recommended before selling or gifting a used Mac. This will securely erase all your personal data, accounts, files and settings from the Mac before ownership is transferred.
Is securely erasing faster than a standard erase?
No, a secure erase actually takes longer than a standard erase or format. Overwriting the hard drive multiple times to meet higher security standards requires added time compared to a quick standard disk format.
Does erasing an SSD wipe it fully?
Not necessarily. SSDs require special tools and techniques like cryptographic wiping to fully secure erase data. Simply formatting an SSD may not overwrite data stored in memory cells.
Is there a way to recover data after a secure erase?
With a full overwrite using software that meets Department of Defense wiping standards, it becomes nearly impossible to recover data from a drive. There is residual risk of forensic recovery, but it is extremely limited.
Can you wipe a fusion drive on Mac?
Yes, Disk Utility allows you to securely erase fusion drives. Start up in Recovery mode, choose your fusion drive and click the Erase tab to wipe it.
Conclusion
Securely wiping your Mac gives you peace of mind when getting rid of an old machine. Make sure your data is backed up first. Then use the Disk Utility method or a secure delete app to overwrite the hard drive. Reinstall macOS for a complete refresh. With a wiped drive, you can safely sell, donate or recycle your Mac.
