Quick Answer
To securely erase a Mac drive in Disk Utility, open Disk Utility, choose View > Show All Devices, select the correct physical drive or volume, click Erase, choose a format, and confirm. For an internal startup drive, you must first start the Mac in macOS Recovery because macOS cannot erase the disk it is currently using.
On Macs with solid-state drives (SSDs), Disk Utility may not offer secure-overwrite options. The most reliable protection is to erase the drive and ensure it is encrypted with FileVault before erasing. On a traditional hard disk drive (HDD), Disk Utility may offer Security Options for overwriting data.
Warning: Erasing a drive permanently deletes its files, apps, accounts, and partitions. Back up anything you need before continuing. Verify the drive name and capacity carefully before clicking Erase.
Before You Erase the Drive
Secure erasing is useful when you are selling, giving away, recycling, or repurposing a Mac drive. It can also resolve certain partitioning or formatting problems, but erasing is not a substitute for backing up or repairing a disk.
Before opening Disk Utility:
- Back up important files. Use Time Machine or another backup method, and confirm that the backup contains the files you need.
- Sign out of services if you are transferring the Mac. Sign out of Apple Account services, Messages, and other accounts as appropriate. This prevents the next user from inheriting access to your accounts.
- Keep the Mac connected to power. An interruption during erasure can leave the drive without a usable volume.
- Disconnect other external drives. Leaving only the drive you intend to erase connected reduces the chance of selecting the wrong device.
- Record any encryption or recovery information you may need. If FileVault or another encryption system is active, make sure you understand which data has already been backed up and which credentials are required.
If the drive is not visible in Disk Utility, check the physical connection and power source first. You can also review how to fix a startup disk not showing on Mac.
Choose the Correct Erasure Method
The right procedure depends on whether you are erasing an external drive, a secondary internal volume, or the Mac’s startup disk.
Erasing an external or secondary drive
You can usually erase an external drive or a volume that is not being used to start macOS directly from the normal desktop. Disk Utility can unmount the selected volume and format it.
Erasing the startup disk
You cannot normally erase the active startup volume while macOS is running from it. Start the Mac in macOS Recovery, then use Disk Utility from the Recovery environment.
- On a Mac with Apple silicon, shut down the Mac, then press and hold the power button until startup options appear. Select Options, then click Continue.
- On an Intel-based Mac, shut down the Mac, turn it on, and immediately press and hold Command (⌘)-R until the Apple logo or a spinning globe appears.
If Recovery does not start or the internal drive is missing, use Apple’s available startup and recovery options for your Mac. Avoid erasing anything until Disk Utility clearly identifies the intended drive.
How to Erase a Drive in Disk Utility
These steps apply to an external drive or a non-startup volume. For the startup disk, follow the Recovery instructions below.
1. Open Disk Utility
Open Finder, select Applications in the sidebar, open the Utilities folder, and double-click Disk Utility.
You can also open it with Spotlight by pressing Command-Space, typing Disk Utility, and pressing Return.
2. Show the complete device list
In the Disk Utility menu bar, choose View > Show All Devices.
This view displays the physical drive, its container, and the volumes inside it. The hierarchy is important:
- Physical device: The actual SSD, HDD, USB flash drive, or external enclosure.
- Container: A storage structure used by some macOS file systems, including APFS.
- Volume: A usable formatted section that appears in Finder.
Select the physical device when you want to remove all partitions and recreate the drive’s partition map. Select an individual volume when you only want to erase that volume and leave other volumes or the existing partition structure intact.
3. Select the correct drive
Use the sidebar to identify the drive by its name and capacity. Click the device or volume you want to erase.
Do not rely on the name alone. Several drives can have similar names, while capacity and connection type can help distinguish them. If you are uncertain, cancel the operation and disconnect unrelated drives before trying again.
Warning: Selecting the wrong item can erase another volume or an entire physical drive.
4. Click Erase
Click Erase in the Disk Utility toolbar.
A dialog appears with options for the new name, format, and partition scheme. The available choices depend on whether you selected a physical device, container, or volume.
5. Enter a name and choose a format
Enter a recognizable name, such as Macintosh HD or External Backup.
Choose a format based on how you will use the drive:
- APFS: A suitable choice for Mac computers using modern macOS, especially SSDs and other flash storage.
- Mac OS Extended (Journaled): Useful for some older Mac workflows and traditional hard drives. It is not usually the first choice for a drive intended for current macOS installations.
- ExFAT: Useful when the drive must be read and written by both macOS and Windows. It does not provide the same Mac-specific features as APFS.
- MS-DOS (FAT): Intended mainly for older devices and smaller cross-platform storage. It has file-size and volume limitations.
If you are erasing a physical device and Disk Utility offers a Scheme menu, choose GUID Partition Map for a drive intended for modern Macs. Older hardware or specialized devices may require another scheme.
6. Select security options when available
On some traditional hard disk drives, clicking Security Options displays a slider or other choices for overwriting the disk. A more thorough overwrite can make previously stored data harder to recover, but it takes longer.
The button may be unavailable for SSDs. This is expected: repeated overwriting is not considered a dependable secure-erasure method for flash storage because of wear leveling and the way SSDs manage blocks internally.
If Security Options is available:
- Click Security Options.
- Select the level appropriate for your situation.
- Click OK.
- Continue reviewing the erase dialog before confirming.
For everyday resale or recycling of an encrypted Mac, erasing the encryption keys and removing the volume is generally more practical than repeatedly overwriting an SSD. If you need protection against highly specialized data recovery, consider using the drive manufacturer’s secure-erase feature or physically destroying the storage device through a professional recycling service.
7. Confirm the erasure
Review the selected device, name, format, and scheme one more time. Click Erase, then click Done when Disk Utility finishes.
The process may take from a few seconds to much longer, depending on the drive, the selected security level, and whether Disk Utility is creating a new partition structure.
Warning: Do not disconnect the drive, close the Mac’s lid, or shut down the Mac while the erase operation is in progress.
How to Erase the Startup Drive in macOS Recovery
Use this method when you want to erase the internal drive that contains macOS.
1. Start macOS Recovery
Shut down the Mac completely.
- Apple silicon: Press and hold the power button until Loading startup options appears. Click Options, then click Continue.
- Intel: Turn on or restart the Mac while holding Command-R. Release the keys when the Apple logo or a spinning globe appears.
If prompted, select an administrator account and enter its password.
2. Open Disk Utility
In the Recovery window, select Disk Utility, then click Continue.
Choose View > Show All Devices so the physical internal drive and its volumes are visible.
3. Select the internal physical drive
In the sidebar, select the top-level internal drive, not only the volume named Macintosh HD. Confirm the drive’s capacity and internal connection details.
If you want to preserve another volume on the same physical drive, do not erase the entire device. Select only the volume you intend to remove, provided Disk Utility allows that operation.
4. Erase the drive
Click Erase. Use a name and format appropriate for the macOS installation you plan to use. For most current Mac installations, APFS with GUID Partition Map is the appropriate configuration when those choices are available.
Click Erase, wait for the operation to finish, and click Done.
If Disk Utility presents an option to erase a volume group, follow the on-screen description carefully. Erasing a volume group removes related system and data volumes together.
5. Quit Disk Utility
Choose Disk Utility > Quit Disk Utility or close the window. You will return to the Recovery utilities.
After erasing the startup drive, you must reinstall macOS before the Mac can start normally. In the Recovery window, choose Reinstall macOS, then follow the installation prompts. The Mac may need an internet connection, and installation can take time.
If you are selling or giving away the Mac, you can stop at the setup assistant after reinstalling macOS. Do not complete the setup with your personal Apple Account.
Troubleshooting Disk Utility Erasure Problems
The Erase button is unavailable
You may have selected a volume that is currently in use or an item that cannot be erased in the current environment. Start macOS Recovery if you are trying to erase the startup disk. Also check whether the selected item is locked, mounted, or part of a structure that requires selecting its parent device.
Disk Utility reports that the erase failed
First, confirm that the correct device is selected and that the drive is connected securely. Disconnect unnecessary peripherals and try again from macOS Recovery if the target is an internal disk.
If the drive may have file-system errors, run First Aid from Disk Utility before erasing it. First Aid checks and repairs certain directory and formatting problems, but it cannot fix every hardware failure. You can review how to repair a Mac disk with First Aid.
If errors continue, the drive may be failing. Copy any accessible data immediately and consider replacing the drive.
The drive does not appear
For an external drive, check its cable, adapter, power supply, and enclosure. Try another port without using a hub. In Disk Utility, make sure View > Show All Devices is enabled.
If the internal startup disk is missing in Recovery, do not repeatedly erase or repartition other visible disks. The problem may involve the drive, its connection, firmware, or the Recovery environment.
Security Options is missing
This commonly occurs with SSDs and flash storage. Disk Utility does not provide the same overwrite controls for every drive type. For an encrypted SSD, erasing the volume removes access to the existing data, but no software-based process should be described as an absolute guarantee against every possible recovery technique.
The drive is still visible after erasing
Erasing normally creates a new empty volume, so the drive will still appear in Disk Utility and Finder. The files should be gone, but the storage device itself remains available. If you need the drive to be completely unusable, physical destruction or a manufacturer-supported secure-erase process may be necessary.
Frequently Asked Questions
Does erasing a Mac drive securely delete everything?
It removes the selected volumes, file-system structures, and accessible data. The level of protection against recovery depends on the drive type, encryption status, and method used. SSDs do not reliably support traditional overwrite-based erasure through Disk Utility.
Should I erase the volume or the entire physical disk?
Erase the volume if you want to remove only one volume. Erase the physical disk if you want to remove all partitions and recreate the entire drive. Selecting the physical disk is destructive to every volume on it.
Is APFS the best format for a Mac drive?
APFS is generally the appropriate choice for a drive used primarily with a current macOS installation, particularly when the storage is an SSD. Choose ExFAT when cross-platform Windows compatibility is more important.
Can I erase the startup disk from normal macOS?
No. You normally need macOS Recovery because the Mac is actively using the startup disk. Recovery lets Disk Utility operate on the internal system drive.
Will erasing the disk remove macOS?
If you erase the physical startup disk or the macOS system volume, macOS will no longer be available to start the Mac. Reinstall macOS from Recovery afterward if you plan to continue using the computer.
Final Thoughts
Disk Utility can securely prepare a Mac drive for reuse, sale, or recycling, but the safest procedure depends on the storage technology. Back up your files, identify the physical drive carefully, use Recovery for the startup disk, and choose the available security options only when they are appropriate for the drive. For SSDs, encryption and proper erasure are more practical than repeated overwriting.