


How to use the cipher /w command to wipe free space on a drive in Windows
Jul 30, 2025 am 04:45 AMThe cipher /w command securely wipes free space on an NTFS drive by overwriting it in three passes: first with zeros (0x00), then ones (0xFF), and finally random characters, making file recovery extremely difficult. To use it, open Command Prompt as Administrator, then run cipher /w:C: (replacing C: with the target drive letter). The process takes significant time depending on free space—100 GB may take over 30 minutes—and shows no progress bar. It only affects deleted files’ free space, not existing files, and requires an NTFS-formatted drive. On SSDs, effectiveness is reduced due to TRIM and wear leveling; for higher security, use BitLocker encryption followed by format, manufacturer tools, or diskpart clean with /p option. While not military-grade, cipher /w is a free and effective method for basic data sanitization on HDDs.
The /w
switch in the Cipher command is a built-in Windows tool that securely wipes the free space on a drive, making it much harder to recover previously deleted files. This is useful for privacy and security, especially before disposing of or repurposing a drive.

Here’s how to use cipher /w
to wipe free space:
What Does cipher /w
Do?
When you delete a file in Windows, the data isn’t actually erased—it’s just marked as "available" space. Tools can recover that data until it’s overwritten. The cipher /w:C
command (for example) overwrites all free space on drive C: with three passes:

- First pass: Writes
0x00
(all zeros) - Second pass: Writes
0xFF
(all ones) - Third pass: Writes random characters
This complies with basic data sanitization standards and helps prevent file recovery.
Step-by-Step: Using cipher /w
-
Open Command Prompt as Administrator
- Press
Win S
, type cmd - Right-click Command Prompt and select Run as administrator
- Press
-
Run the cipher /w command
- Type the following, replacing
C:
with your target drive letter:cipher /w:C:
- Example:
cipher /w:D:
- Type the following, replacing
-
Wait for the process to complete
- This can take a long time, depending on how much free space is on the drive.
- For example, wiping 100 GB of free space might take 30 minutes.
- You’ll see no progress bar—just wait until the command prompt returns.
?? Note: The drive must be formatted with NTFS.
cipher /w
won’t work on FAT32 or exFAT drives.
Important Considerations
- Only affects free space: It does not erase files currently on the drive—only the space marked as "available."
- SSDs vs HDDs: On SSDs, this method may be less effective due to wear leveling and TRIM. It’s still useful, but full drive encryption (like BitLocker) or hardware-based secure erase is better for SSDs.
- Disk space required: The drive must have enough free space to allow the overwrite process. If the drive is nearly full, free up space first.
- System performance: The process is resource-intensive. Avoid heavy usage during the wipe.
Alternative Secure Erase Methods (For SSDs or Sensitive Data)
If you're dealing with an SSD or need higher security:
- Use BitLocker Drive Encryption and then format (encrypt-then-erase method)
- Use manufacturer tools (e.g., Samsung Magician, Intel SSD Toolbox)
- Use
diskpart clean
orformat
with the/p
(passes) option for full overwrites
Using cipher /w
is a simple, no-cost way to help protect your privacy on NTFS drives. It's not military-grade, but it's effective for most users wanting to securely clear deleted data. Just remember: patience is key—it takes time.
The above is the detailed content of How to use the cipher /w command to wipe free space on a drive in Windows. For more information, please follow other related articles on the PHP Chinese website!

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