Why wont my Windows let me format a USB drive?

There are a few common reasons why Windows may not allow you to format a USB drive. Here are some quick answers to this question:

Common Reasons Windows Won’t Format a USB Drive

  • The USB drive is write protected or locked
  • The USB drive has a partition that is currently in use
  • There is a file open on the USB drive
  • The USB drive is corrupted or damaged
  • Insufficient user permissions to format the drive
  • Antivirus software blocking the format
  • The USB drive uses an unsupported file system

If Windows is giving you an error or not allowing you to format your USB drive, one of those issues above is likely the cause. We’ll explore each of these in more detail below and discuss solutions to allow formatting the drive.

The USB Drive is Locked or Write Protected

Many USB drives have a physical write protection switch on the housing. This switch can be slid to the locked position to prevent files from being written to the drive. If your USB drive write protection is enabled, Windows will not be able to format the drive.

To disable write protection, slide the switch on the USB drive housing to the unlocked position. This will allow the drive to be formatted. Write protection is useful to avoid accidental changes or corruption of data on the drive.

How to Check a USB Drive Write Protection Status

To check if your USB drive is write protected in Windows:

  1. Connect the USB drive to your computer
  2. Open File Explorer and locate the USB drive
  3. Right click on the drive and select Properties
  4. Under the General tab, see if “Read-only” is checked. If so, write protection is enabled

You can also look for a physical write protection switch on the USB drive housing and make sure it is slid to the unlocked position.

A Partition on the USB Drive is In Use

If your USB drive has multiple partitions, one of the partitions may be currently mounted and in use by Windows. If so, Windows will not allow formatting the entire drive.

For example, your USB may have a primary partition and a smaller hidden recovery partition. If that recovery partition is mounted, the whole drive cannot be formatted until that partition is unmounted.

To check for partitions on your USB drive:

  1. Go to File Explorer
  2. Right click on the USB drive and select Manage
  3. In Disk Management, see if multiple partitions are listed on the drive

If there are multiple partitions, try unmounting any that are active. Right click on the partition and select Change Drive Letter and Path. Remove any drive letter assignments to unmount the partition.

Once all partitions are inactive, Windows should allow formatting the full USB drive.

A File is Open on the USB Drive

If any files on the USB drive are currently in use or open, Windows cannot format the drive. For example, if you have a document open from the USB drive, it needs to be closed before formatting can occur.

Make sure to close all files that may be on the USB stick before trying to format it. Also make sure no applications or explorer windows are accessing files on that drive.

How to Check for Open Files on a USB Drive in Windows

You can use the following steps to check for open files on your USB drive that may prevent formatting:

  1. Open File Explorer and locate the USB drive
  2. Right click on the drive and select Manage
  3. Click on Computer Management > System Tools > Shared Folders > Open Files
  4. Look for any open files on the USB drive listed and close them

Closing any open files or applications using the USB should allow formatting to work.

USB Drive Corruption or Damage

If your USB flash drive is corrupted or physically damaged, Windows may have trouble formatting the drive.

Some signs your drive may be corrupted:

  • Errors accessing files or copying data
  • Unreadable folders or files
  • Strange crashes or screen freezes when using drive

Try scanning the USB on your computer for errors. To scan for errors:

  1. Open File Explorer and right click on USB drive
  2. Select Properties > Tools tab > Click Check button
  3. Allow scan to run and repair any found errors

If the error scan is unable to repair problems with the drive, it may need to be replaced due to physical damage or corruption. Replacing the USB stick with a new drive should allow Windows to format it.

Insufficient User Permissions

On Windows computers, you need administrative privileges to format a drive. Standard or guest user accounts may not have permissions to format a USB device.

To format a drive, make sure you are logged into an Administrator account on your computer. If you are using a Standard or Guest user profile, switch to an Admin account or ask an Administrator to format the USB drive for you.

How to Check Your User Account Type on Windows

Follow these instructions to confirm your account type in Windows:

  1. Open the Start Menu and click on the Settings cog
  2. Click on Accounts
  3. Under Your Info, check if your account type says Administrator, Standard User, or Guest

If your account is not an Administrator, you will need to switch users or have an Admin format the USB drive.

Antivirus Software Blocking Format

Antivirus programs can sometimes interfere with formatting a USB drive. The antivirus may mistakenly block the format process believing it is an unsafe operation.

To rule out antivirus blocking as the issue:

  1. Temporarily disable your antivirus completely
  2. Try formatting the USB drive again

If formatting works with the antivirus disabled, you will need to add an exception for your USB drive to your antivirus to allow formatting it while keeping protection active.

Adding Exceptions to Popular Antiviruses

Here are guides on adding exceptions for USB formatting to popular antivirus tools:

Follow your specific antivirus support documentation to add an exclusion for USB drive formatting.

Using an Unsupported File System

If your USB drive is formatted with an unsupported file system, Windows will be unable to format over it.

Windows can typically format USB drives to FAT32 or exFAT formats. Occasionally a drive may have a Linux file system (Ext4), NTFS, or other unsupported format.

To check the file system on your USB drive:

  1. Open File Explorer and locate the drive
  2. Right click and select Properties
  3. Under General, look at the File System listed

If the file system says NTFS, Ext4, HFS+ or anything other than FAT32 or exFAT, Windows cannot format the drive normally. You will need to use third party formatting tools to erase and reformat the USB to a Windows compatible file system before using it.

Third Party USB Formatting Tools

Some free tools that allow formatting USB drives to FAT32 or exFAT in Windows include:

Use one of those tools to completely reformat your USB drive and overwrite any unsupported file systems. Once reformatted to FAT32 or exFAT, Windows should be able to format the USB drive normally.


Windows refusing or giving errors when trying to format a USB drive is usually caused by one of the common issues mentioned. Enabling write access, unmounting partitions, closing open files, scanning for errors, adjusting user permissions, configuring antivirus exclusions, or using third party tools to put the drive in a supported format will typically resolve most problems formatting a USB device.

Following the troubleshooting steps outlined for the various potential causes, you should be able to get your USB drive formatted properly so it can be used as needed on your Windows computer.