What to do right now
- If the stick holds data you need, recover or copy it first.
- Run a read-only check for signs of fake capacity.
- Confirm with a full write-and-verify test only on an empty device.
Step by step
Recognise the warning signs
Very low price for a large capacity, unknown brand, photos or videos that become corrupt after the card fills up, and files that open fine at first and later show garbage.
Save your data first
Copy or recover the files you need before any test. A full capacity test writes the whole device and destroys what is on it.
Run the read-only check
In Disk health & tools, run the fake capacity check. It looks for address wraparound, where high addresses map back onto low ones, and for mismatches between the file system size and the device size, without writing anything.
Confirm with a full test
On an empty device, use a write-and-verify tool such as H2testw or f3. It fills the device with known data and reads it back, which reveals the real capacity exactly.
Decide what to do with it
Return it to the seller if you can. If you keep it, use it only for unimportant data and only up to its real capacity.
How fake capacity works
The device's controller is programmed to report, say, 1 TB, while the memory chip holds 32 GB. Writes beyond the real size wrap around and overwrite earlier data, or are discarded. Windows cannot detect this, because the controller answers every request as if everything were fine.
Formatting does not reveal the problem, because a quick format writes only a little data. Only writing and reading back the whole device does.
Typical victims are cheap high-capacity USB sticks, microSD cards and portable SSDs sold through online marketplaces. Dashcams and action cameras that record continuously are hit hardest, because they fill the card quickly.
Can data on a fake card be recovered?
Data that was within the real capacity and not overwritten by the wraparound can be recovered like on any card. Data written beyond the real size was overwritten or never stored correctly; no software can bring it back.
Limits of the check
- The read-only check finds strong signs, not proof; a full write test is needed to confirm.
- A genuine but failing card can also corrupt data; the symptoms overlap.
- Files that were overwritten by the wraparound are gone.
How FileFix Ultimate helps
- Runs a read-only fake capacity check that looks for address wraparound and size mismatches.
- Recovers deleted and lost files from the card before you run a destructive test.
- Reports confidence and evidence instead of a yes-or-no verdict.
- Never writes to the device it checks.
FileFix Ultimate is free, works offline and never writes to the drive you are recovering from. Check the signature before you run it.
Frequently asked questions
Why not just run the write test right away?
Because it overwrites everything. If the card holds photos you need, recover them first.
Can a fake stick be fixed?
The memory cannot be made larger. Some tools can repartition it to its real size, but quality is often poor too.
Does Windows show the real capacity?
No. Windows shows what the controller reports, which is the fake value.
Are branded cards from marketplaces safe?
Counterfeits often copy well-known brands and packaging. Buy from the manufacturer's official store or a reputable retailer, and test new cards before trusting them with important data.