A drive that will not format after a capacity test is alarming — and a format failure after testing is a clue, not just a malfunction. Depending on the pattern, it can tell you something precise about the drive: about the file system it can honestly sustain, about a Windows dialog limitation that is not a fault at all, or about a fake controller that cannot survive being written to honestly. This guide separates those cases.
For the testing context itself, see our guides to the two modes — the Quick Size Test and Test Empty Space — and for the closely related symptom of a drive vanishing altogether, our guide on a USB drive that disappeared after a test. The tool itself is on the download page.
Why fakes live on FAT32 — and struggle with NTFS
The developer’s explanation starts with how the two file systems lay out their structures. A fake drive’s controller reports a large capacity while a small chip provides the real storage. FAT32 keeps its essential structures relatively compact and toward the start of the volume, so a fake can be formatted FAT32 and appear to work: Windows writes the structures where real storage exists, and casual use stays plausible for a while.
NTFS is less forgiving of the lie. It places its directory around the 3 GB mark and keeps a backup sector at the very end of the partition. On a fake, that end-of-partition location may not exist as real storage at all, and the directory placement probes regions the controller is faking. The result can be a format that fails, stalls, or completes into a volume that immediately misbehaves. This is exactly why fakes are usually sold formatted FAT32, and why a drive that flatly refuses an NTFS format while claiming a huge capacity is showing you evidence about itself. The file system did not break the drive; it asked questions the drive could not answer honestly.
The innocent case: Windows will not offer FAT32 above 32 GB
Separate from fakes entirely, Windows has a long-standing dialog quirk: its built-in format window will not offer FAT32 for volumes larger than 32 GB, even though FAT32 itself can support much larger volumes and Windows will happily use a large FAT32 volume formatted another way. Users testing a genuinely large drive, wiping it after a destructive Quick Size Test, regularly meet this and assume something is broken. Nothing is: choose NTFS or exFAT in the Windows dialog for a large genuine drive, or use a tool that can format large FAT32 volumes if FAT32 is genuinely required for a device’s compatibility.
That tool, in this tool’s own family, is RMPrepUSB — the developer’s main program, from the same author as FakeFlashTest. RMPrepUSB can format large volumes as FAT32 where the Windows dialog will not. If your need is a big FAT32 volume for a camera, console, or older device, that is the practical route. Keep the distinction straight, though: “Windows will not offer the option” is a dialog limit; “the format itself fails partway with errors” is a drive talking, and on a high-capacity bargain drive it is usually confessing.
What to try, in a sensible order
First, retry the format in Disk Management rather than Explorer, deleting the existing volume and recreating a simple volume at full size — and if the drive’s contents matter, stop: formatting is destructive, and everything here assumes an empty or backed-up drive whose test is complete. Second, match the file system to the purpose: NTFS or exFAT for a large genuine drive in Windows use; FAT32 via RMPrepUSB only when a target device truly needs FAT32. Third, observe where a failure happens. A format that errors when writing structures near the end of a huge claimed capacity, on a drive that also failed its capacity test, is one story told twice.
Try the drive on another port and, if available, another computer before declaring it dead; a reader or port fault can masquerade as a format failure just as it can hide a drive from testing tools. But do not loop endlessly through format attempts on a confirmed fake, expecting a combination of settings to succeed. No file system choice repairs missing hardware.
The verdict underneath: a fake is still a fake
Here is the sentence to keep hold of: successfully formatting a fake drive — even coaxing it into a working FAT32 volume sized to its claim — does not make it genuine. The real capacity is the chip, not the format. Such a drive will still wrap around and overwrite older files once writes pass its real limit, and the format’s success merely restarts the clock on that discovery. If FakeFlashTest has shown the capacity to be false, the drive’s future is a refund claim with the test log as evidence, not a formatting project.
Conversely, a genuine drive that hit only the 32 GB dialog limit, or needed its volume recreated after a destructive test, is healthy — format it appropriately and use it with confidence. Telling those two situations apart is the whole skill: dialog limits and post-test repartitioning are normal; end-of-partition failures on a drive that failed its capacity test are a confession. When in doubt, retest cleanly with the tool from the download page rather than arguing with the format dialog — the capacity verdict settles what the format error means.