How to erase empty space on Mac

Hello KhushiRatra,

Your agent is right—simply deleting files or reformatting doesn’t truly erase data. Remnants remain in the free space and can be recovered.

Since your Mac likely has a traditional HDD and runs an older macOS (probably Mojave 10.14 or earlier), the free space wipe feature is still available. Here’s how to securely erase it:

Option 1: macOS Disk Utility (Built-in)

1. Open Disk Utility (/Applications/Utilities).
2. Select your volume (e.g., “Macintosh HD”)—not the physical drive.
3. Go to File → Erase Free Space… or check Security Options.
4. Choose a security level:

• 3-Pass Erase: Secure and faster.
• 35-Pass (Gutmann): Maximum security, but can take many hours.

Option 2: Professional Wiping Tools

For selling or agency verification, use certified third-party tools:

• BitWipe Drive Eraser for Mac: Meets global standards (DoD, NIST) and provides a Certificate of Destruction. - But I believe it can be expensive for a everyday user - yet they have a sale going on - You can reach out to their customer support.
• Other cheaper tools: BleachBit, BitRaser (wipes file traces) or DBAN (wipes entire drive, requires bootable USB).

Using these methods ensures your free space is securely erased and gives you peace of mind when selling your Mac.

In that case, this article will cover all needed steps:

What to do before you sell, give away, trade in, or recycle your Mac - Apple Support

Do you want to erase your Mac and give it away?

Erase your Mac and reset it to factory settings - Apple Support