• External drives
  • Troubleshooting

Your 64 GB USB stick shows 200 MB on the Mac: getting the full size back

A USB drive or SD card that shows far less space than it should usually has a leftover partition. How to see it in Disk Utility and restore the full size.

4 min read

A 64 GB stick that shows 200 MB, or 4 GB, or nothing at all. This happens most after a drive was used as a macOS or Windows installer, a Raspberry Pi card, or a camera card. The rest of the space is still there, in a partition the Mac does not show in Finder.

See every partition

diskutil list external

Look for your drive, usually /dev/disk4 or similar. If it has several partitions, or one with an unusual type like Linux or EFI, the space is locked up in those. Disk Utility shows the same thing if you choose View, Show All Devices.

Getting the full size back

  1. Open Disk Utility and choose View, Show All Devices.
  2. Select the top-level device, the one named after the maker, not the volume under it.
  3. Click Erase, choose ExFAT or APFS, and GUID Partition Map.
  4. Click Erase. The drive comes back with its full capacity.

If Disk Utility refuses, Terminal can do the same. Check the disk number carefully first, because erasing the wrong disk is permanent:

diskutil list external
# then, with YOUR disk number:
diskutil eraseDisk ExFAT USBSTICK GPT /dev/disk4

If it is still small

  • Some fake drives report a size they do not have. A cheap 2 TB stick can really be 32 GB. Writing beyond the real size silently loses files. If a drive was very cheap, test it before trusting it.
  • The numbers are slightly lower than the label. A 64 GB drive shows about 62 to 64 GB, because makers count in round decimal numbers and some space goes to the file system. That is normal. The same effect on your Mac is in why a 256 GB Mac shows less space.

Once it is the right size, the format to choose depends on which computers will use it.

Common questions

Why does my USB drive show less space than it should on Mac?

Usually because an earlier use, such as an installer or a Raspberry Pi, left extra partitions. Erasing the whole device in Disk Utility, with Show All Devices on, restores the full capacity.

Is it normal for a 64 GB USB stick to show 62 GB?

Yes. A small difference is normal. A large one, like showing 4 GB, means leftover partitions or a counterfeit drive.

How do I see hidden partitions on a USB drive on a Mac?

Run diskutil list external in Terminal, or open Disk Utility and choose View, Show All Devices.

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