How do I restore my USB flash drive to full size?

If you find that your USB flash drive is showing less available storage space than it should, there are a few things you can try to restore it to full capacity. Here are some quick answers to common questions about restoring USB flash drive space:

Why does a USB flash drive show less space than advertised?

There are a few main reasons why a USB flash drive may show less available storage space than expected:

  • Pre-installed files – Many USB drives come with some pre-installed software, files or partitions that take up space.
  • Formatting – How the drive is formatted can result in some storage space being inaccessible. For example, drives formatted with FAT32 cannot store files larger than 4GB.
  • Bad sectors – Damaged areas on the drive that cannot store data anymore are called bad sectors. These can result in lost space.
  • Cluster size – How data is organized and written to the drive affects how efficiently space is used. Large cluster sizes can waste space.

How can I check the real capacity of my USB drive?

To check what the actual full capacity should be for your USB flash drive, you can look at:

  • Model name/number – Look up specs online for your model, which will list the advertised capacity.
  • Printed info – Capacity is often printed on the drive itself or packaging.
  • Plug in and check properties – View the properties in Explorer (Windows) or Finder (Mac) to see capacity.
  • Use disk utility – Tools like Disk Management (Windows) or Disk Utility (Mac) show full capacity.

This can help you determine if your drive is showing less space than it should have available.

How can I restore the full capacity of my USB drive?

If your flash drive shows less space than expected, here are some steps to try to restore its full storage capacity:

  1. Delete unneeded files – Permanently delete any files you no longer need from the USB drive.
  2. Safely eject and re-insert the drive – Reconnect the drive to force it to re-mount.
  3. Run CHKDSK (Windows) / First Aid (Mac) – These utilities check and repair drive errors.
  4. Format the drive – Completely reformatting erases all data but can fix capacity issues.
  5. Remove write protection – Check for a small switch on the housing that enables write protection.
  6. Create new partition – Use disk management tools to delete all partitions and create a new one.

In many cases, simply deleting unnecessary files or reformatting the drive can restore the full advertised storage capacity. But if that doesn’t work, more advanced fixes like creating a new partition may be necessary.

How to check USB flash drive space on Windows

On Windows, there are a few ways to check the available storage space and capacity of a connected USB flash drive:

  • Open File Explorer, click on the flash drive letter and look at the available space shown.
  • Right-click the drive letter and select Properties. This will show total capacity and free space.
  • Open Disk Management. Find your flash drive, right-click and select Properties to view the total size and free space.
  • Use the command line. Open Command Prompt and type “dir x:” where x is your flash drive letter to see capacity info.

You can also use third-party tools like a USB formatter or partition manager to get details about the full capacity and any issues with a flash drive.

How to check USB flash drive space on Mac

On a Mac, you can check USB flash drive storage space and capacity in a few different ways:

  • Finder – Open a new Finder window, click on your flash drive in the sidebar and look at the available space shown.
  • Get Info – Right-click on your flash drive icon on the desktop or in Finder and select Get Info. This will show capacity details.
  • Disk Utility – Open Disk Utility, select your flash drive and click Info to see total capacity and space used.
  • Terminal – Open Terminal and use the command “df -h” to see storage details for connected drives.

Third-party Mac utilities like OmniDiskSweeper or DaisyDisk can also provide visual representations of your flash drive’s used and free space if you want more details.

How to format a USB flash drive

Formatting a USB flash drive erases all data but often fixes issues with reduced capacity or drive errors. Here are the basic steps to format a drive:

On Windows:

  1. Open Windows File Explorer.
  2. Right-click on your USB drive and select “Format…”
  3. Choose the file system – FAT32 or exFAT are common for flash drives.
  4. Check the Quick Format box.
  5. Click Start to begin formatting.

On Mac:

  1. Open Disk Utility.
  2. Select your flash drive in the sidebar.
  3. Click Erase near the top toolbar.
  4. Choose a name, format (MS-DOS FAT is common) and scheme.
  5. Click Erase to format the drive.

Reformatting the drive will wipe all data but often resolves issues with reduced available space on USB flash drives.

How to fix bad sectors on a USB drive

Bad sectors are damaged areas on a USB flash drive that cannot reliably store data. They can result in lost storage capacity. To detect and fix bad sectors:

  • Run CHKDSK (Windows) or First Aid (Mac) – these utilities scan for bad sectors and attempt repairs.
  • Use disk utility tools like HD Tune or Disk Checker to scan for bad sectors.
  • If the drive uses flash memory, try reflashing the controller chip to remap bad areas.
  • Format the USB drive – formatting marks bad sectors as unusable and blocks them off.
  • As a last resort, physically destroy and replace drives with extensive bad sectors.

While bad sectors cannot be fully restored, disk utilities can often recover the lost space by marking damaged areas as unusable.

How to remove write protection from a USB drive

If your USB flash drive has a physical write-protect switch, you’ll need to disable that before you can format, erase or restore the drive to full capacity. The small switch is often located on the housing of the drive.

  • Carefully slide the write-protect switch on the housing to the off position if it is currently on.
  • If the switch is already off, try toggling it on and off again anyway.
  • Check for any error messages about write protection when trying to format or delete files.
  • As a workaround, try copying files to the flash drive when it is write-protected to fill up the space.
  • If no switch is present, the drive itself may be damaged and write protected.

Resolving any physical write-protection issues will allow for file operations needed to restore the full storage capacity.

How to repair a corrupted USB flash drive

If your USB flash drive becomes corrupted or unreadable, try the following steps:

  1. Use CHKDSK (Windows) or First Aid (Mac) disk repair utilities to fix errors.
  2. Reformat the flash drive to fix file system issues.
  3. Try plugging the drive into another computer or USB port in case the issue is with the connection.
  4. Check for physical damage to the drive housing and connectors.
  5. If the drive doesn’t appear at all, try using data recovery software to access it.
  6. As a last resort, destroy and replace the damaged USB drive if unrepairable.

USB corruption issues can often be repaired with disk utilities or reformatting. But significant physical damage may require getting a new flash drive.

How to recover data from a corrupted USB drive

If important files and data on your corrupted USB flash drive need to be recovered, try these options:

  • Use recovery software like Recuva or TestDisk to scan and extract data from damaged drives.
  • Connect the USB drive to another computer in case the USB port is causing corruption.
  • Attach the drive to a Linux system which can sometimes read corrupted drives that Windows can’t.
  • Take the drive to a data recovery specialist for advanced physical repair and recovery.
  • Dig through Recycle Bin and backups like cloud storage to find copies of lost files.

USB drive data recovery is possible in many cases thanks to advanced software and services – but the more damaged the drive, the lower the chances of getting files back.

Can you restore full capacity after formatting a USB drive?

Yes, reformatting a USB flash drive can often restore the full advertised storage capacity after showing less space. Formatting erases files and rebuilds the file system to efficiently reclaim all available drive sectors.

Reasons reformatting may help restore full USB drive capacity include:

  • Eliminating fragmented data or unnecessary partitions taking up space.
  • Wiping hidden system files or pre-installed software no longer needed.
  • Marking bad sectors as unusable so they don’t show as available space.
  • Correcting issues in the file table caused by corruption or disconnected removal.

However, if physical damage exists or the manufacturer overstated the size, reformatting may not help. But for software issues, it often resolves lost space problems.

Steps to restore full capacity after formatting USB drive

  1. Copy any files you need off the USB drive first
  2. Use Windows Explorer or Mac Finder to quickly reformat the drive
  3. Choose the FAT32 or exFAT format for maximum compatibility
  4. Select the option for a quick format to erase space faster
  5. Safely eject and reinsert the freshly formatted USB drive
  6. The drive should now show its full capacity restored

Just remember that formatting deletes all data, so be sure to transfer any important files first before proceeding.


Restoring the full advertised capacity of a USB flash drive is often possible with some basic troubleshooting steps. By deleting unneeded files, formatting the drive, fixing bad sectors, removing write protection and repairing corruption, you can usually reclaim lost space.

However, if physical damage exists or drive errors persist, you may need advanced recovery software or professional data recovery assistance. At some point it may be necessary to replace the USB flash drive completely if it has failed irreparably.

But in many cases, simply reformatting and removing redundancies can restore a USB drive’s full size. With the right tools and disk management techniques, you can easily maximize your available flash drive storage capacity.