I have a USB drive which I format with

sudo mkfs.vfat -I /dev/sdb1

When I then look at the size of the USB drive with df -h, it reports its size to be 64 MB, though it should be 8 GB. What am I doing wrong?

fdisk -l /dev/sdb1 gives

Disk /dev/sdb1: 67 MB, 67108864 bytes
241 heads, 62 sectors/track, 8 cylinders, total 131072 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

     Device Boot      Start         End      Blocks   Id  System
  • 1
    It looks like this USB drive has several partitions. What's the output of fdisk -l /dev/sdb? Jul 27, 2014 at 20:02
  • Edited the question.
    – pfnuesel
    Jul 27, 2014 at 21:17
  • Not fdisk -l /dev/sdb1 (which lists the partitions inside the partition sdb1). Run fdisk -l /dev/sdb. Jul 27, 2014 at 21:21

1 Answer 1


It should be mkfs.vfat -I /dev/sdb. sdb1 indicates you probably have more than one partition, and you're just formatting the first one, which happens to be 64MiB.

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