Format of Sandisk Ultra USB3.0

I have 2 SanDisk ultra 128 GB thumb drives.
1st is original format FAT 32 with 2 partitions 1 is 31MB unallocated the other is 117.3 GB Healthy
Primary. There is a quick start guide on it.

2nd I formated I can selct from exFAT or NTFS format max of 115GB. How can I format to original size?
I am using windows 10.


Hi @BigAl4638,

Please be informed that what you are observing is the difference in the definition of one Gigabyte by operating systems versus product manufacturers. Operating systems use a binary system which will present a lower number of GB than the decimal-based system used by manufacturers to define the capacity of products. This is due to the binary system representing a GB as a higher number of actual bytes.

For example: Operating systems define a 1GB as 1,073,741,824 Bytes. We define 1GB as 1,000,000,000 bytes.

To understand this difference in definition better, you may refer to the following articles from our online Knowledge base:

If further assistance is needed, please open a case with our support team at the following:

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Hi Keerti_01,
I understand GB etc. What I don’t understand is why capacity on 2 identical drives is different. The original format is FAT32 has 126,164,697,544 bytes. Fat32 is not an option on Windows 10. The one I reformatted as NTFS has 115GB/124,216,406,016 bytes. How can I recover the lost space? Thanks, Al

Here is what I see

You can completely clear and reset the partitions and master boot record by using the diskpart utility included in every Windows OS system.

The diskpart command interpreter helps you manage your computer’s drives.

Back up all your data first before attempting this

  • Open Command Prompt (cmd) in administrator mode
  • Type in diskpart
  • Type in list disk
  • Select the option with the USB you want to reset
  • Type in clean
  • Type in convert mbr
  • Type in create partition primary
  • Then format the USB to your preferred settings

    What the commands do:
  • The clean command removes any and all partition or volume formatting from the disk with focus
  • The convert mbr command converts an empty basic disk with the GUID Partition Table (GPT) partition style into a basic disk with the master boot record (MBR) partition style
  • The create partition primary creates a new primary partition
  • Format it to be able to use it


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Brnkm, Thanks for the instructions.
Unforturnately, the result was the same! the Windows 10 format olny gives me a size of 115GB to use. Some how it came with 117GB but I cannot format it back to 117GB.
Thanks, for your help!

I also have a Sandisk Ultra 128GB Thumb driver with two NTFS partitions. Thank you for the advice on how to reset the partitions. moviebox pro , 3utools Although I have other thumb drivers, the Sandisk is the most reliable and has the quickest data transmission speed. I enjoy Sandisk products.

Actual answer is this, file systems and sector size will affect free space. The file system itself uses space, the more granular the file system the more space it will take, with a trade off that it will handle small files with less waste.

There is no lost space. If you want to store large files use large cluster exfat, if very small files, use a small cluster size.


There is a 2 gb difference in space between the one I reformated and the one I didn’t! 117 gb vs 115 gb. I didn’t expect 128 gb for the reasons you mentioned. I was hoping to find a method to recover the missing space.

Its not missing, its just file system loss.

You can lose far more than 2GB if you have large clusters and a ton of small files as files can’t share clusters and so the partially filled are just waste. Its just a trade off.


Both drives are empty. One is the way it came new 117gb the other I formated to the largest size the format program listed 115 gb. I was hoping to find a format method to recover the space.
Somehow SanDisk was able to format to 117 gb.

They must have different default cluster settings, check using chkdsk.