Quick Capacity
Writes position-aware samples across 256 regions, reads them back, checks for address aliasing, then verifies restoration of original sampled data. Useful as an early warning—not a byte-for-byte capacity guarantee.
Blackwire Flash Media Tester — USB & SD Card Capacity Verification
Blackwire Flash Media Tester checks advertised capacity, data integrity, readable storage, and performance before you trust a USB drive or memory card with important files.
Run a sampled check, read the full reported surface, benchmark performance, or perform a destructive full write-and-read verification when you need stronger evidence.
Free and $5 Support include exactly the same software. Full Write + Verify erases the selected device.
CapacitySampled checks and full-device verification
IntegrityRead-back, address, and I/O failures
PerformanceRead/write speeds and benchmark data
EvidenceRegion maps, test history, and PDF reports
Why capacity verification matters
A drive can report 2 TB without actually storing 2 TB.
Windows may show the advertised size even when the device cannot reliably store and return data across that address range. A few successful small-file copies don't establish the full capacity.
Verify a new USB drive or SD card before it becomes the only home for photos, backups, or important documents.
What to look forWritten ≠ verified
A successful write response means little if the bytes read back are wrong—or return from the wrong location.
See how the tests differReal hardware case study
An advertised 2 TB USB drive failed verification.
One flash drive purchased through Amazon was tested using Blackwire Flash Media Tester. This is one device's test result, not a claim about every seller or device.
Advertised capacity2 TB
Failed sampled regions255 / 256
What the test establishesData integrity failed
What happened
The reported capacity could not be trusted.
Position-stamped sample data failed verification in 255 of 256 regions. We could not establish reliable storage across the advertised address range.
A short 256 MiB Burn-In workload could still pass in limited testing. That does not establish the drive's full capacity; the broader failure must take precedence.
The takeaway
A successful small-file test doesn't prove a drive can safely hold its advertised capacity.
A result you can trust
A short test cannot clear a capacity failure.
The current Burn-In workflow requires appropriate capacity-validation evidence on an unverified device and preserves an existing failure. Even a completed limited workload cannot change a failed drive into “healthy.”
We did not establish the drive's true physical capacity. The test evidence shows that its reported storage could not be trusted.
The test workflow
Start with a quick check. Go deeper when the job calls for it.
Different tests answer different questions. The tool labels their scope so a limited pass is not mistaken for complete capacity proof.
Read Surface
Reads the reported address range and records read errors or persistent slow-response areas without intentionally writing test data.
Full Write + Verify
Writes test data across the entire selected device and reads it back to check capacity and integrity. All existing data on that device is erased.
Benchmark
Measures sequential and random read/write performance, IOPS, latency, and transfer-size behavior. Speed alone does not prove capacity.
Burn-In / Soak
Exercises flash storage with repeated write, read, and verify cycles. Capacity prerequisites and existing failure results prevent a short successful run from overruling broader evidence.
Results & reports
Inspect error counts, region maps, device test history, and export a PDF report with available verification evidence. A reported result describes the work actually performed.
Inside the application
See what the tests actually report.
Real screenshots of Blackwire Flash Media Tester. Select an image to view the full interface without cropping.
Who it helps
Useful before a new card or drive holds real data.
Home users
Check newly purchased USB drives and memory cards, especially when advertised capacity and price don't seem to match.
Technicians & IT
Qualify removable storage before deployment and keep repeatable results for troubleshooting and documentation.
Photographers & creators
Test SD and microSD cards before relying on them for photos, footage, and other files that are hard to replace.
Download Flash Media Tester
Free software. Optional support.
Both options provide exactly the same complete application. Paying $5 is voluntary support for continued development, not a feature upgrade.
Complete application
Free
$0
Get the full Flash Media Tester with every current feature at no cost.
- Quick and full capacity verification
- Read Surface, Benchmark, and Burn-In
- Results and PDF reporting
- No feature restrictions
Voluntary development support
Support Development
$5
The exact same software as Free, for anyone who wants to help fund future updates and testing.
- Same complete application as Free
- All current features included
- No extra features or unlocks
- Supports continued development
Both options include the same complete software. Support is entirely optional and helps fund continued development.
Installer or portable?
Flash Media Tester is available in installer and portable formats. Choose the format that suits the job; Free and Support have identical functionality.
Safety first
Know which test writes data.
- Back up important files before testing any storage device.
- Quick Capacity writes and restores sampled blocks. Unexpected failures can still damage data—use a backup.
- Full Write + Verify is destructive and erases all data on the selected device.
- A quick test, a short Burn-In, or a benchmark pass cannot guarantee full advertised capacity.
- If verification fails, do not trust the device with important data.
Frequently asked questions
Does Quick Capacity prove my drive is genuine?
No. It verifies sampled regions. Full Write + Verify is needed to check the full reported capacity.
Will Full Write + Verify erase my files?
Yes. It overwrites the selected device. Back up your files and confirm the target drive before you begin.
Does passing Burn-In establish the full capacity?
No. Burn-In checks the exercised workload; the tool keeps capacity validation as a separate prerequisite and does not let a limited pass cancel a recorded capacity failure.
Is the $5 version different from Free?
No. Both are the same complete application. $5 is voluntary support for Blackwire development.
Which storage devices can I test?
USB flash drives, SD/microSD cards, and similar flash storage exposed as supported Windows storage devices. Hardware behavior and available tests can vary.
Blackwire Flash Media Tester
Test the storage before you trust it.
Check capacity and integrity with the complete free application. Choose Support only if you'd like to help keep it in development.