What is full format USB?

USB (Universal Serial Bus) is a common interface used for connecting devices to computers and other electronics. There are different formats and standards for USB devices, with full format being one of the most common.

What does full format mean for USB drives?

Full format refers to completely formatting and wiping a USB flash drive to restore it to factory default settings. This process erases all data and partitions on the drive and recategorizes it to be compatible with the computer’s file system.

When you full format a USB drive, the following things happen:

  • The file allocation table (FAT) or file system is overwritten and recreated.
  • All existing folders and files are deleted.
  • The drive is repartitioned and recategorized as a bootable disk.
  • Any bad sectors are mapped out.
  • The flash memory is cleared of any electrical charges.

In simple terms, full formatting removes everything on the USB drive and restores it to the same blank state it had when it was new.

Why would you fully format a USB drive?

There are several reasons why you may want to fully format a USB flash drive:

  • To securely erase all data before donating or recycling the drive.
  • To remove any partitions and reformat as a bootable disk.
  • To troubleshoot errors caused by corrupt files or bad sectors.
  • To restore full storage capacity that may be reduced by fragmentation.
  • To scan and fix file system issues that cause problems accessing the drive.
  • To eliminate any malware or viruses that may have infected the USB drive.

In most cases, full formatting is only necessary if you want to completely wipe the drive or are having technical problems with it. Regular use of USB drives only requires quick formatting which is faster and does not scrub the entire drive.

How is full format different from quick format?

The main differences between full format and quick format are:

Full Format Quick Format
Completely erases data by overwriting file tables and file system structures. Only empties the index to make space available for new data. File data still exists on the drive until overwritten.
Scans drive for bad sectors and attempts to repair them. Does not scan or fix bad sectors.
The process takes much longer, from several minutes to hours depending on the drive size. Typically takes just seconds because no overwriting is done.

As the table illustrates, the main advantage of quick formatting is it only takes a short time. But full formatting is more secure and helps resolve any underlying problems with bad sectors on the disk.

How to fully format a USB drive on Windows

To full format a USB drive on Windows, follow these steps:

  1. Insert the USB drive into your computer.
  2. Open Windows File Explorer and click on This PC in the left panel.
  3. Right click on the USB drive and select Format from the menu.
  4. In the Format window, choose exFAT or FAT32 file system.
  5. Check the Quick Format box to uncheck it.
  6. Click Start to begin the full format process.
  7. Wait for the format to complete. This may take several minutes for a large capacity drive.
  8. When finished, the USB will be fully wiped and reformatted.

Using the full format option will scan and fix errors compared to quick formatting. Be aware this will erase all data on the drive.

How to fully format a USB on Mac

To full format a USB drive on Mac OSX, use these steps:

  1. Connect the USB drive to your Mac.
  2. Open Disk Utility, usually found in Applications > Utilities.
  3. Select the USB drive in the left side panel.
  4. Click Erase across the top menu.
  5. Choose a name, format (MS-DOS FAT, ExFAT, or APFS) and Scheme (GUID or Master Boot Record).
  6. Click Erase to start the full format process.
  7. When finished, the drive will be fully erased and reformatted.

Following these steps in Disk Utility will format the entire USB drive, wiping all previous data and reconfiguring the file system for Mac OS.

How to fully format a USB using Command Prompt

You can also full format a USB or flash drive from Command Prompt in Windows. Here are the steps:

  1. Connect the USB drive to your computer.
  2. Open the Command Prompt window as administrator.
  3. Type diskpart and press Enter.
  4. Type list disk and note the disk number of your USB drive.
  5. Type select disk x (replace x with your disk number) and press Enter.
  6. Type clean and press Enter to delete all data on the disk.
  7. Type create partition primary to recreate the main partition.
  8. Type format fs=fat32 quick to quick format the partition.
  9. Type exit when finished to close DiskPart.

Using the clean command will accomplish a full format on the USB drive. Be very careful to choose the correct disk number of the USB drive when using diskpart commands.

Should you fully format a new USB drive?

Most new USB flash drives come already formatted and ready for use right out of the package. But there are a few reasons you may want to fully format a brand new USB drive:

  • To test the drive and scan for any bad sectors or defects.
  • To format it to a file system your computer recognizes.
  • To format a very large drive (64GB+) with FAT32 instead of exFAT.
  • To remove any partitions or pre-loaded software on the drive.
  • To wipe it before using for an important purpose like backing up data.

For everyday use, quick formatting a new USB is fine. But fully formatting doesn’t hurt and gives you the chance to initialize the drive from a blank state.

How to check if a USB drive is fully formatted

You can check whether a USB flash drive has been fully formatted by looking at these signs:

  • The format was done through disk management, command prompt, or Mac Disk Utility without quick format.
  • The drive has very little if any stored data on it.
  • The volume name of the drive has been changed from the default.
  • The file system was reinitialized as FAT32 or exFAT format.
  • There are no longer multiple partitions shown for the disk.
  • The full drive capacity is available when checking properties.

Usually you will know a drive has been fully formatted recently if you completed the process yourself. But in some cases, checking the above items can help confirm if a full format occurred.


Full formatting completely erases and reinitializes USB flash drives to fix problems, wipe sensitive data before recycling, or remove malware. It is more thorough than quick formatting but takes longer. On Windows, use the full format option in File Explorer or the clean command in diskpart. On Mac, use Disk Utility and select erase. Fully formatting is useful to restore USB drives to original settings.

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