I have a HP flash drive with 8 GB capacity. Recently I tried to copy a file larger than 4 GB to it(when the flash drive was empty) and got an error(saying something like "cannot copy, insert another disk"). So I googled and found that it is the problem of the FAT32 file system. I formatted the flash drive as NTFS file system and then I was able to copy the file.

Now I will tell what I want to know. When formatted as FAT32 there was 7.47 GB available to use. When formatted as NTFS the capacity became 7.49 GB, but only 7.42 GB was available(7.42 GB free of 7.49 GB). So opened flash drive to know what is consuming 0.07 GB but found nothing.

Why the capacity of flash drive changes in FAT32 and NTFS ? In NTFS what is consuming 0.07 GB of my flash drive ?

  • 1
    Believe it of not, all drives (including flash drives) have different sizes depending on the file system format.
    – LDC3
    Oct 15, 2014 at 2:30

2 Answers 2


The cluster size, the smallest amount of disk space that can be used to hold a file [1], would be the same for NTFS as FAT32[1]. This is a confusing point, and this makes this a good question. Why then would there be differences in formatting sizes? As already mentioned, there are more features built into NTFS than FAT32. NTFS provides things beyond FAT such as metadata on files (file name, creation date, access permissions and sometimes contents), security access control lists, and file system journaling. These features improve reliability, security and flexibility; but they also lead to slightly higher space constraints, which one sees when the cluster sizes are the same. It is important to note that if your USB were larger, NTFS tiers for cluster sizes increase more slowly than FAT32. So, you would see the reverse of your observation in larger USB drives [1].

The largest contributor to the discrepancy in size difference is the difference in sizes of the tables that are used to keep track of which files are where on the USB drive.

FAT32 uses the File Allocation Table, which is simpler and smaller than the Master File Table in NTFS.

"NTFS reserves 12.5 percent of the volume for exclusive use of the MFT until and unless the remainder of the volume is completely used up" [2].

The complexity of comparing the reserved space is beyond the scope of this answer, but I can refer you to further search parameters like "reserved space," "MFT versus FAT size, and "boot sector."

[1] http://support.microsoft.com/kb/140365 [2] http://support.microsoft.com/kb/174619

  • Well answered. The links were helpful. Oct 15, 2014 at 4:22

There is a significant increase in the amount of disk space overhead required for an NTFS partition as compared to a FAT partition. This is why on small volumes you will generally find it formatted as a FAT partition.

  • NTFS requires extra space to store security descriptors, at the very least.
    – LawrenceC
    Oct 15, 2014 at 2:22
  • Will you describe it a little further ? Oct 15, 2014 at 2:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.