How to Restore USB Drive/Flash Drive/Pen Drive Back to Full Capacity

Daisy updated on Oct 13, 2020 to Partition Master | How-to Articles

Overview of USB flash drive not showing the full capacity

Sometimes, users may find that their USB flash drive is not showing full capacity. For example, you have a 16 GB USB flash drive, but Windows shows only 3 GB. The same issue can happen to other storage devices like hard drives, pen drive, memory card, Micro SD card, etc. When you happen to come across such a problem, how can you reclaim the lost space and restore USB flash drive back to full capacity or original size? Don't worry, even you have no reliable solution. After introducing how to restore the SD card back to full capacity in the last article, here on this page, we will continue discussing the reasons and fixes for USB flash drive not showing the full capacity issue. 

Why USB flash disk showing wrong capacity

When your USB flash drives or other removable disks are not showing the original size, you may wonder how it happens or where the lost capacity disappears. Generally speaking, there are various reasons that will mistakenly display the actual disk space of a flash drive or an external disk. For example:

  • It's made to be a bootable USB disk with a portable Windows operating system on it.
  • The flash drive has more than one partition on it. Windows will only recognize the first partition.
  • There is a hidden recovery partition or unallocated space that does not show up in the PC.
  • The 64GB or 128GB USB flash drive is formatted with an improper file system (FAT32) in Windows.
  • Some viruses did damage to the removable disk or the card reader/host devices are not well suited for some types of memory cards.

How to restore USB drive back to full capacity

According to the mentioned causes that will possibly result in a USB drive losing some disk space, the solutions to restore the USB drive back to full capacity should vary on different operating systems. Here in the following, you'll learn a full guide to get back USB flash drive's full storage size on Windows, macOS, and Linux.

On Windows 10/8/7:

To restore USB drive, pen drive or flash drive back to full capacity, you can use a third-party USB format tool to reformat the flash drive. EaseUS Partition Master allows you to format the USB flash drive, hard drives, pen drive, memory card, Micro SD card and recover the lost disk space or unallocated space when disk shows the wrong capacity in Windows. 

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 Windows 10 is supported

Formatting will erase all the data, please make sure that you have made a backup before trying to restore USB drive, pen drive or flash drive back to full capacity.

To restore USB drive, pen drive or flash drive back to full capacity, follow these steps:

Step 1: Select the USB drive to format.

Connect the USB drive or pen drive to your computer. Download and launch EaseUS partition software. Right-click the USB drive you intend to format and choose "Format".

Format Hard Drive Partition - Step 1

Step 2: Set the drive letter and file system.

Assign a new partition label, file system (NTFS/FAT32/EXT2/EXT3), and cluster size to the selected partition, then click "OK".

Format Hard Drive Partition - Step 2

Step 3: Check the warning box.

Click "OK" if you see the Warning window. If you have important data on it, back up the data in advance.

Format Hard Drive Partition - Step 3

Step 4: Apply the changes.

Click the "Execute operation" button first, and then click "Apply" to format the USB drive.

Format Hard Drive Partition - Step 4

On Mac OS X & macOS:

Step 1. Connect the wrong-size USB flash drive to your Mac.

restore usb drive back to full capacity mac step 1

Step 2. Go to Applications > Utilities > Double click and open Disk Utility.

restore usb drive back to full capacity mac step 2

Step 3. Select your USB flash drive on the sidebar, choose Erase.

Step 4. Rename the USB flash drive, choose the format as MS-DOS (FAT) for Format, Master Boot Record for Scheme. Then click Erase.

restore usb drive back to full capacity mac step 3

On Linux:

Step 1. Delete all partitions

  • Open a terminal and type sudo su.
  • Type fdisk -l and note your USB drive letter.
  • Type fdisk /dev/sdx (replacing x with your drive letter).
  • Type d to proceed to delete a partition.
  • Type 1 to select the 1st partition and press enter.
  • Type d to proceed to delete another partition (fdisk should automatically select the second partition).

Step 2. Create a new partition

  • Type n to make a new partition.
  • Type p to make this partition primary and press enter.
  • Type 1 to make this the first partition and then press enter.
  • Press enter to accept the default first cylinder.
  • Press enter again to accept the default last cylinder.
  • Type w to write the new partition information to the USB disk.
  • Type mkfs.vfat -F 32 /dev/sdx1 (replacing x with your USB key drive letter).

What else can help restore a USB flash disk back to full capacity?

Deleting all partitions on the USB drive and reformatting should be the most effective ways to regain the USB drive's full capacity. Nonetheless, they are not the unique troubleshooting for all cases of the USB drive showing the wrong capacity.

As some bad sectors or corruption issues will also cause the flash drive, memory card or external hard drive not showing its original size, it might help to fix corrupted USB flash drive using CMD.

If you don't have any technical know-how and want to minimize data risks, using third-party software could be a better choice. The Command line is suitable for computer professionals since wrong commands can cause severe problems. Therefore, we strongly recommend you try an automatic command line alternative.

EaseUS Tools M is a practical computer fixing tool that is safe and light-weighted. It's a perfect alternative to CHKDSK command. Use this one-click tool to solve your computer issues.

To fix file system error or disk error:

Step 1: DOWNLOAD EaseUS Tools M for Free and install it.

Step 2: Open the software and select the "File showing" option. 

Step 3: Choose the drive and wait for repairing. After the operation completes, click the "View" button to check the drive. 

select the drive and check off file system error

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Will the "Migrate OS" feature transfer the Windows system files only or the whole C drive?

To ensure that the migrated system will boot normally, the Migrate OS feature will transfer all the files in the system and the boot partitions. Generally, the boot partition is the C drive so the transfer will include all the files in C.

Does EaseUS Partition Master license apply to multiple computers?

The license of Partition Master Professional and Server editions can be used on 1 computer only, while that for for the Technician and Unlimited editions can be used on multiple machines.

What is the difference between EaseUS Partition Master Trial version and the Free version?

Free is for home users only, with most basic functions available such as partition resize and clone. While trial can help you understand how this product works and test what a full license can do on a business or server OS machine.

Will it cause any data loss after resizing the partition in EaseUS Partition Master?

Generally, it will not cause any data loss or boot issue by resizing a partition. However, in order to protect your data, we suggest that you backup the partition before resizing, in case of any unexpected situations such as power outages, computer hardware failures, etc. You can use EaseUS Todo Backup to backup the partition and its trial version is fully functioned for 30 days.

What should I prepare before resizing the partition?

On the partition that is going to be operated, there might be some files being occupied by other programs. To ensure a successful operation, we suggest that you close all the unnecessary software before resizing that partition. Otherwise, EaseUS Partition Master will detect the partition being locked by the other software and require a reboot to resize the partition under boot mode.

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