16 gb shows up as 200 mb

I removed U3 from from my ultrabackup 16 gb using the mac utility. When I use a windows computer it says the drive is not formatted and then can only make a 200 mb partition.  How do I fix this? Thanks Sandisk.

I can confirm that I have the same problem. I am also surprised SanDisk has not yet posted a solution for this…

Ok I figured it out. When you are in disk utility on the mac, click the main disk which is your flash drive. Then you get a partition option. Click on that and you can see a small square which is the 200 MB partition and a larger square which is the second partition.  Click just below the volume scheme and set it to 1. The size of the new partition will show 16 GB. Rename it and change the format to Fat. click apply and you are done. I formatted it on a windows PC and got 14.9 GB now.

Thank you jamesqu for the update.  :smiley:

If you cannot find Partition Tab, check this out:


I am using windows xp , am not getting a partition tab .

1 Like

Hi James, were you able to fix this already? How abut starting from scratch and do the format in a Windows XP computer instead.

dwaynnyt:: “Hi James, were you able to fix this already?

It certainly appears that he did.

jamesqu: “Ok I figured it out.”


Old thread but here is the solution.  For me every program that looks at the thumb drive was reporting wildly different sizes.  Physically it was reading 29GB.  But the partition/format was reading like 8MB.  After looking at the drive I realized they were trying to use a old school FAT32 partition.

On these larger drives (Larger than 4GB) you can end up with issues with FAT32.  It should actually be formated exFAT.  WHICH is actually more compatiable with modern OS’s and thumb drives.

On my Windows 8.1 system I reformatted the drive to exFAT format and everything read up just fine.  Also the format might have been glitched in transition.  Like it might have gotten too close to something magnetic screwing up the partition information.  BUT no matter what exFAT is better for your thumb drive.