By AOMEI / Last Updated May 15, 2020

Why should USB drive lost capacity?

When your USB drive is not showing full capacity, you may wonder that how it happens. Actually, there are various reasons can cause this issue. For example, after using a freeware image burner to burn a portable operating system on your 4GB removable drive, you may find that your USB drive lose all its space. If you open Windows Explorer, right click the USB drive icon, select properties and you’ll see the available space show is only 250GB or else without full capacity. This is because some OS will change the partition of removable device so that there will be free space on your USB drive. In addition, using some third-party software to do an inappropriate and unsuccessful formatting may also cause inaccessible portion on your USB drive shown as unallocated space. There are still other reasons, and there is a solution to restore USB drive back to full capacity - using third party USB format toolto reformat the USB drive.

How to restore USB drive back to full capacity?

About how to restore USB drive back to full capacity, you may first think of performing a quick

format with Disk Management disk-partitioning tool since the partition on USB drive might be rewritten, unfortunately, this problem can’t be solved with such normal tool. You need a third party USB format tool to solve the problem with USB drive that shows wrong capacity, and we recommend AOMEI Partition Assistant to you.

AOMEI Partition Assistant has a free edition which is powerful enough to solve this problem, and you can use it within all Windows editions including Windows 7/8/10/XP/Vista of both 32bit and 64bit. Apart from format, it also supports to wipe disk, wipe partition, create partition, resize partition and so on. Next, we’ll show to how to successfully restore USB drive to full capacity via free AOMEI Partition Assistant.

1. Download, install, and launch AOMEI Partition Assistant Standard edition.

2. Right click on the existing partition on your USB drive and select “Format Partition”. (Reformat will delete all data on partition, so please backup before the operation.)

Format Partition

3. In popup window, choose the file system as FAT32 or NTFS. Click “OK” to proceed.

Choose File System

Now you can restore USB drive back to full capacity by resizing the reformatted partition to full drive space through “Resize Partition” function.

Resize Partition

4. You can preview the result here and don’t forget to click “Apply”.


It’s so convenient to restore USB drive back to full capacity with AOMEI Partition Assistant. Also, with so many other features, you can use it to easily solve other problems such as fix MBR in Windows 10, etc.