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I have an 8GB Sony USB memory stick and only 49 MB are being detected. I've tried on multiple USB ports and tried formatting it several times.

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I checked it for errors and it said none are found. I want to use it to install Windows 8 off of but 49MB is way too small.

By the way, what's the most universally accepted name: thumbdrive, usb memory stick, jump drive, flash drive (I thought flash memory was for digital cameras)?

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    I wonder if you have two partitions on it (which windows won't pick up). The alternative is the disk could be faulty.
    – Journeyman Geek ♦
    Commented Feb 15, 2015 at 3:55
  • @JourneymanGeek Luu Vinh Phuc was right, I copied a bootable ISO to it and the new partition is only 49MB. The trouble is in diskmgmt.msc the option to extend the partition is greyed out.
    – Celeritas
    Commented Feb 16, 2015 at 3:52

3 Answers 3

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Probably you've flashed some boot USB or ISO image which have size of only ~49MB. That process clears the flash drive's MBR and replaces it with the one in the image that contains a small partition. You can verify that by opening diskmgmt.msc and check if there is only a single 49MB partition

If that's correct then just delete and recreate the partition. Or use some 3rd party partitioning tools like gparted, or EaseUS® Partition Master or MiniTool® Partition Wizard Home Edition to extend/recreate the partition

Another GUI solution is Rufus

Help, how do I restore my USB to how it was before I created a bootable drive?

So, you created a bootable drive, possibly with a DD image, and now Windows no longer seems to see it, or it reports that its capacity is much smaller than it actually is. And now you want to "restore" it to a state where you could just use it to copy files, with Windows recognizing the drive and letting you use its full capacity.

Well, what you really want to do is "restore" your drive to non-bootable state. And, of course Rufus has a very prominent way to allow you to do that.

See the Boot selection dropdown in Rufus? The one that has a Non bootable entry? Well, if you select that option, and then pick whatever you want for the file system, then Rufus will happily "restore" your media to something Windows will recognize, with full capacity, and that you can use again to transfer files. That's all there is to it.

If you don't want to use GUI then there's the built-in diskpart that you can read about its usage in the other question

See also

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  • Yes I did flash memtest. So that screwed it up? Extend and shrink volume are greyed out in diskmgmt.msc
    – Celeritas
    Commented Feb 15, 2015 at 3:35
  • Yes, flashing a disk image clears the whole MBR and partition table and overwrite it with the new partition table of that image. Since the table has only 1 49MB partition, you only see this. Sometimes it's worse when you use some ISO image, because in that case Windows only recognizes it as a CD and you can't repartition it anymore unless you use some external partitioning tools
    – phuclv
    Commented Feb 15, 2015 at 3:39
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You don't need to use external partition software. I had the same exact issue and for the same exact reason:

  1. Start command prompt

  2. Type diskpart

In the new window:

  1. type list disk

  2. type select disk x (replace x with your disk number as determined by the previous command)

  3. type clean

  4. type create partition primary

You can now go to disk management and format the disk.

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    Accepted answer doesn't explain where the options in diskmgmt.msc are (greyed out for me or just not appearing). This did the trick without weird GUI hassle, thanks.
    – a p
    Commented Oct 24, 2016 at 0:21
  • @ap I said "delete it and recreate the partition" which means exactly like clean then create partition primary in this answer. There's no way to extend or shrink in this case
    – phuclv
    Commented Mar 19, 2017 at 4:38
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    @LưuVĩnhPhúc The options are greyed out in Disk Management, you cannot perform them there for some reason.
    – zrooda
    Commented Jun 24, 2017 at 18:09
  • Worked like a charm. Thanks
    – SeriousTyro
    Commented Jan 25, 2022 at 15:48
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Did you try using a different computer to see if that solves the problem?

Usually, flash drives are detected based on the amount of available space that can be used for reading/writing to the disk. You could try a full format once (not quick format), and then try formatting again to see if more space is available.

Flash drive is the most generally accepted term, I think, but they all are pretty much the same thing. Thumb drive and memory stick are kind of 2000s though.

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