How to Fix Not Enough Free Space on USB Flash Drive But There Is

When you copy or transfer a file to a USB flash drive, your flash drive might say there is not enough free space even though there is. Here we will explain why it occurs and share effective solutions for your reference.


By Michael / Updated on November 29, 2023

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Why "not enough space on USB flash drive but there is" occurs?

An error warning stating: "not enough space on the USB" may appear when you attempt to generate or transfer large files onto an external hard drive or USB flash drive. To make disk space available, remove one or more files, and then try again.

"At the same time, Windows suggests using "Disk Cleanup" to free up disk space by removing old or unnecessary files—a condition that appears to be related to a "drive full" issue. The truth is that there is more than enough space on the device to hold these files.

What may be causing this error message to appear?

• File System Limitations:  This is the main reason that will cause the error. As you may know, USB flash drives, by default, are formatted with the FAT32 file system which has a 4GB maximum single file limit. That's to say, no matter how much free space your flash drive has, you will get this error when you transfer a single file that is larger than 4GB to the USB drive. 

• File Corruption: If the file you are trying to transfer is corrupted, the system might interpret it as taking up more space than it actually does.

• Temporary Files: The drive might be filled with temporary files or cached data that are not immediately visible.

• Drive Errors: There may be errors on the USB flash drive, such as bad sectors, that are affecting its capacity and causing the system to misreport the available space.

What to do when there is not enough space on USB flash drive but there is some?

From the above, we can learn the cause is that the USB flash drive is of FAT32 file system. And the error may be much possibly appear when you need to copy large files to a USB. To get around this problem, the easiest way is to change the file system from FAT32 to NTFS which has no file size limit.

Then how to change FAT32 to NTFS file system? If there is not any important data in the USB flash drive, you can directly reformat USB to NTFS. If there is important data, you can use the following 2 methods to directly convert FAT32 to NTFS without reformatting.

Method 1. Convert FAT32 to NTFS using CMD

If you are familiar with the Windows command line, you probably know Convert.exe which can help you convert FAT partition to NTFS. It can help you convert FAT or FAT32 to NTFS file system easily.

1. Press the "Windows" key and "R" key simultaneously to bring up "Run" window.

2. Type “CMD” in the box and press Enter.

3. In the pop-up command prompt window, type: "convert x: /fs:ntfs" (“x” represent the drive letter of your flash drive). For example, if you want to convert drive D: to NTFS, you can type “convert D: /fs:ntfs”


In a few seconds, the process tells you when conversion is complete. Once it is converted to NTFS, you cannot convert it back to FAT32 or FAT using the same way. If, however, this conversion fails due to no enough free space, you can use another tool to solve this problem that flash drive says not enough space but there is.

Method 2. Convert FAT32 to NTFS with freeware

AOMEI Partition Assistant Standard is a piece of third-party software that allows you to convert FAT32 to NTFS and NTFS to FAT32 without data loss. You can follow the steps below to get it done.

Download Freeware Win 11/10/8.1/8/7/XP
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Step 1: Download and run AOMEI Partition Assistant. In the main interface, click “Convert > Convert to NTFS/FAT32”.

NTFS to FAT32 Converter

Step 2: In the pop-up window, select the option “FAT32 to NTFS”.


Step 3: Then all the FAT and FAT32 formatted partition will be listed. Just select your USB flash drive and click “Next”.

FAT32 Partitions

Step 4: Click “Proceed” to confirm and proceed.

Proceed FAT32 to NTFS

In seconds, a window will prompt out to notify you that the conversion is complete.

Tip: If you still want to format your USB, you can use CMD or AOMEI Partition Assistant to execute the operation. AOMEI Partition Assistant has "Data Recover" function that can help you retrieve lost data from formatted devices.


Both ways can help you get your USB back to normal if you see a prompt saying not enough space on USB flash drive but there is. But AOMEI Partition Assistant can solve the problem without cleaning data on your USB. Also, it can convert NTFS to FAT32 without data loss. What‘s more, because Windows 11 only supports UEFI boot mode, if you want to try Windows 11, please convert MBR to GPT wihout data loss.  

FAQs about not enough space on USB flash drive but there is

How do I check the file system of my USB flash drive?
Right-click on the drive, select "Properties," and go to the "General" tab. The file system type will be displayed. Ensure it supports the size of the files you are trying to transfer.

What should I do if there are hidden files taking up space on the USB flash drive?
Enable the display of hidden files in File Explorer. Delete unnecessary hidden files or move them to another location. Be cautious not to delete system-critical files.

What steps can I take to check for and fix disk errors?
Right-click on the drive, select "Properties," go to the "Tools" tab, and click on "Check." Follow the on-screen instructions to scan and fix any disk errors.

Are there specific USB flash drive brands or models prone to this issue?
This issue is generally related to system and file factors rather than specific brands or models. It can occur with any USB flash drive.

Michael · Staff Editor
Michael is a professinal editor of AOMEI editor team.