9 Free USB Flash Drive Tester & Checker Tools [Best in 2025]
Many cheap or counterfeit drives fail unexpectedly, leaving you with lost data and frustrating surprises. While standard tools like Scandisk can detect basic errors, they don’t always catch hidden issues such as fake storage or unreliable read/write speeds.
To get a true sense of your USB drive’s performance and capacity, specialized testing software is essential. In this guide, we’ll walk you through the best USB testing tools to ensure your drive is as reliable as it claims to be.
What is the best USB checker?
| Tool | Primary Function | Test Type / Features | Supported OS | Pros | Cons |
|---|---|---|---|---|---|
| Check Flash | Burn-in testing & speed verification | Read/Write stress tests, burn?in test, speed measurement | Windows | Simple, portable executable; effective for verifying stability and performance | Limited to USB flash drives only; no support for external HDDs |
| RMPrepUSB | USB formatting & capacity verification | Quick Size Test to verify usable capacity; also supports bootloader creation | Windows | Fast capacity check; easy to use; multifunctional (formatting & bootloader testing) | Erases all data on the drive; not a full read/write stress test |
| H2testw | Capacity verification & error detection | Fills drive with test data (1GB chunks) and verifies integrity | Windows | Excellent at detecting counterfeit drives; straightforward and reliable | Can be time?consuming on larger drives |
| Flash Drive/Card Tester | Error and performance testing | Write, read, and compare tests with a graphical device map for errors | Windows | Graphical display of test results; effective for detecting bad sectors and performance issues | Comes as an installer (portable version available); bundled extras may occur |
| USB Memory Stick Tester | Basic error detection | Configurable number of test passes and test size (percentage of capacity) | Windows | Extremely lightweight (only 66KB); simple and portable; good for basic error testing | Very old interface; limited features compared to modern tools |
| F3 (Fight Flash Fraud) | Counterfeit drive detection | Writes and verifies data to check true capacity | Windows, Linux, macOS | Open?source and cross?platform; excellent for detecting fake drives | Command?line interface may be less intuitive for some users |
| USBDeview | USB device information & history | Lists connected USB devices with detailed properties and usage history | Windows | Lightweight; displays comprehensive device info for troubleshooting | Not designed for full drive testing (more of a diagnostic tool) |
| CrystalDiskMark | Speed benchmarking | Sequential and random read/write speed tests with customizable parameters | Windows | Clean and simple interface; great for comparing drive speeds | Focuses only on performance benchmarking, not error detection |
| HDDScan | Comprehensive drive diagnostics | Scans for bad sectors, reads S.M.A.R.T. attributes, checks temperature | Windows | Extensive testing features; supports a variety of drive types including USB flash drives | Dated user interface; Windows?only |
Now, let’s take a look at some more in-depth information abut each USB tester:
1. Check Flash
Check Flash (ChkFlsh) is a very simple flash drive testing and maintaining tool. I have used this tool several times to run a burn-in read-and-write test on USB drives. If the device can survive after a few cycles, the USB flash drive should be OK.
There are 3 access types and 6 action types for you to select. To access the actions of “Read stability test”, “Save image”, “Load image” and “Full erase” you have to change the Access type from temporary file to a logical or physical drive.
Other than checking for drive errors, it can also determine the read and write speed.
The test length can be set to scan the drive just once, several specified passes, or leave it running until an error is found, or you tell it to stop. Check Flash is a free and single portable executable file. It can only test USB flash drive and not external hard drives.
2. RMPrepUSB
RMPrepUSB is a tool which is actually a USB formatting, partitioning, and bootloader creation utility as opposed to a USB testing tool. While it’s not meant to be useful for doing a complete read-and-write scan, it does have a little function that can test your drive to see if there are missing or bad parts and what the actual usable size is.
This is ideal to check if the drive is the capacity you believe it to be and is infinitely quicker than scanning the whole drive if that’s all you want to do.
Make sure the USB drive IS EMPTY because any contents will be deleted. Simply insert your drive and select the “Quick size test”. Portable and installable versions are available. This is also quite a good tool to experiment with bootloaders on your flash drive as there are several different types that can be used.
While the Quick Size Test will give you a general idea of whether the entire size of the drive is available and working, it won’t run a complete test. To do that, you can download FakeFlashTest which is by the same developer and includes the quick test and another more comprehensive test.
3. H2testw
H2testw is able to test USB flash drives, memory cards and also internal, external and even network hard drives for errors. It simply works by filling the device with 1GB chunks of test data and then verifies it by reading the data back again. Usage is very simple. Select the English language because it defaults to German, select the target device, and then choose whether you want to test all available space or a specified amount of Megabytes.
Although H2testw is non destructive in that it won’t overwrite anything present on the drive, for best results, it’s recommended to have an empty and newly formatted device.
This program has been found to be very good at testing both for errors and to find USB sticks with a fake capacity. H2testw is also a completely portable standalone executable.
4. Flash Drive/Card Tester
Flash Drive/Card Tester is a tool we’ve mentioned before because it’s a simple tool but can be used in a few different scenarios.
In addition to being handy useful for detecting fake capacity drives, it can also show you how fast the drive can read and write data. Another thing it’s good for is testing for bad or problematic sectors on a flash drive or memory card.
All you have to do is select the drive to test and choose a “Write, read and compare” test, then start the process.
The device map at the bottom will show a graphic representation of passes, write fails or read fails. Choose the Write log file option to output a possible list of errors to a text file. The program actually comes as a setup installer but we’ve zipped the two files to make Flash Drive/Card Tester Portable.
Flash Drive/Card Tester Portable
5. USB Memory Stick Tester
This tool is very old dating back to 2005 but it still works and is only 66KB in size. USB Memory Stick Tester is a pretty simple tool to operate and will write and then read data to test for errors on the drive. There are only really two options to speak of.
The first thing you can change is the number of passes slider. Although it doesn’t say, we assume it can be one to four possible passes.
The other option is the test size which will be a percentage of the total size of the flash drive. Obviously, the higher the proportion of the drive is tested, the more likely it is that any issues or errors will be identified.
Download USB Memory Stick Tester
6. F3 (Fight Flash Fraud)
F3 is an open-source tool designed to detect counterfeit USB flash drives. Many cheap or counterfeit flash drives may advertise a large storage capacity but only provide a fraction of it. F3 works by filling the drive with test data and then verifying the integrity of the stored information. It’s particularly useful for spotting fraudulent drives that show false available space.
Using F3 is simple: just select the USB device, choose the amount of space to test, and let the program write and verify the data. It’s a great way to ensure that you’re not getting scammed with a flash drive that doesn’t deliver the promised capacity.
F3 is portable and works on Windows, Linux, and macOS.
7. USBDeview
USBDeview is a lightweight utility from NirSoft that provides detailed information about all USB devices connected to your computer, including USB flash drives. This tool is not strictly for testing drive health or capacity, but it’s excellent for checking device properties, including connection history and status. You can use USBDeview to spot any unusual behavior or conflicts with your USB drives.
It’s a great tool for diagnosing issues with your USB ports and attached devices. While it won’t run a full drive test like others, it’s useful for troubleshooting or keeping track of your device usage.
USBDeview is portable and easy to use on Windows.
8. CrystalDiskMark
CrystalDiskMark is primarily known as a benchmarking tool but is a useful utility for testing the read and write speeds of USB drives. This tool provides a series of sequential and random tests to check the performance of your flash drive. It’s especially handy when you’re trying to compare the speed of different drives or testing the performance after a format.
The interface is simple to use: select the drive, choose the test type, and start the process. If you’re concerned about how fast your USB drive is or need to verify speed claims, CrystalDiskMark is a solid choice.
CrystalDiskMark works on Windows and is completely free.
9. HDDScan
HDDScan is a versatile diagnostic tool that can be used to test not only hard drives but also USB flash drives. It allows you to check the health of your drive by scanning for bad sectors, running temperature checks, and even reading S.M.A.R.T. attributes. This is a great all-around tool for monitoring the status of your USB drives, as well as hard drives.
The interface is straightforward, and the program supports a variety of file systems. HDDScan is useful for both simple and advanced diagnostics, offering a lot of options for troubleshooting.
HDDScan is available for free on Windows.
Regularly testing your USB flash drive helps prevent data loss and ensures reliable performance. If you’re storing important files, consider creating a full backup to protect your data.
Curious about past usage? You can track USB devices used on your computer. And if you’re setting up a new system, installing Windows via USB can save time. Youc can also use an online VRAM test tool to verify your GPU.
Proper testing and management keep your drives performing at their best.
thank you very much
2tb flash drive? unless this cost 1000s of dollars it is definitely fake
Buy a M.2 2280 2 TB SSD, put it inside a USB enclosure and voila! There you are. And it doesn’t cost thousands.
I suppose that having 400 hours of remaining process for the ChkFlsh to complete the test is good news about the 2TB flash drive pen I got as a gift… Anyways, I still doubt this strange little thing is really having that damn much capacity lol
Check Flash (ChkFlsh) fails on a read test on the last block for both of my USB drives. Flash_Drive_Tester flags no errors. I don’t trust ChkFlsh and removed it.
Why would you install it then in the first place, if you didn’t trust it? What is the cause of it not reading the last block? Is it related to the drive, or the software? Context is important.
Didn’t the guy have to install it???!!!
How could he have come to not trust it without having installed and tried it? Where are you coming from?
Same here with this program. It fails on almost any drive, that I tested. It is complete s**t. Delete this program.
Worked fine during testing and completed without issue on two or three drives. I can only assume there’s an issue with specific drives/systems/USB devices.
Some of these programs are quite old, and I doubt whether they are able to cope with the larger flash drives available today. For instance, the last Flash Drive Tester version, 1.14, dates back to 2009. I always depended upon it until I bought some 128GB sticks from MyMemory, a reputable supplier, and it reported errors. The company insisted that the sticks were sound, so I tried other programs, like h2Testw, which passed them and they have given no trouble since.
Thanks for presenting these flash drive testing tools, all in one place.
I have some media on order from Groupon that I was subsequently told [after purchase], might be fake.
As soon as I get my Groupon order I will be testing them with these tools.
Been years since I tested a flash drive with these tools. Glad you still had these tools listed online.
Warning re RMPrepUSB: I’ve downloaded and am testing all 3 apps mentioned in this article. I ran the “Quick Size Test” and found that as a result of that test the formatting of the flash drive was deleted. All I wanted to do was have it check for missing/bad portions but got “more” than expected.
It’s not a big deal and I might have done something wrong so my report is mentioned as a FWIW.
Because of this I’ve decided to uninstall RMPrepUSB from my computer.
The program clearly warns you that it is going to erase the drive and you must click OK to continue.
Thanks guys…just found a fake drive…(512gb memory showing and actualy he has only somewhere around 15gb) also usb 2.0 not 3.0 :D so that means…a 16gb memori flash.
You want to be careful on how you test flash drives. Flash memory has a limited number of write/erase cycles (Google “flash endurance” for info). Too many writes to flash when testing could result in premature failure. And never defrag a flash drive since that creates excessive writing to the drive.
While it is true that flash memory has a limited number of write cycles, your concern about longevity is not reasonable. All flash memory on the market has a limit of between 10,000 and 100,000 P/E cycles. (Program/Erase cycles. Each set of Program and Erase functions represent one cycle.) Let’s put this in context. If you have a cheap flash drive that experiences such extreme use that, every day the drive is completely erased and filled to capacity; that flash drive should last 27.39726 years before it reaches complete failure. The heaviest use a flash drive is likely to see is when it is used as a ReadyBoost drive. This is when Windows is allowed to use flash as a buffer for a hard drive. I have two 8 GB drives serving that function and they each see daily use of around 4 GB per day. The expected P/E life is about 13.69862 years. The reality is that any flash drive will fail for other reasons long before you use up your P/E cycles. You also need to consider that the flash drive you favor today, is going to look pretty shabby in 4 or 5 years. Tech standards and data requirements change constantly and your hardware needs to change to keep up with those changes. So while I still appreciate what my pair of 8 GB USB 2.0 flash drives gave me in their time, they still got replaced with my pretty new 64 GB USB 3.0 drive. (It’s 4x the capacity and real world performance for the same price.) Needless to say, I know longer care about the 2.0 drives. And in a few years I won’t care about my 3.0 drive. As if all that were not enough to convince any rational person that P/E cycles are a non issue, the next big leap expected in the NAND architecture is the introduction of 1,000,000 P/E cycles to MLC NAND. (That is highly speculative, but it is the boon the SSD market is hoping for. Think SSD’s that can compete with hard drives in terms of price, capacity and endurance.)
Note, the 10,000 P/E cycle is for 50 nm MLC NAND and 100,000 is for SLC. With smaller lithographies and cheaper NAND pricing, the amount of P/E cycles have actually gone down for NAND used in consumer applications (e.g. consumer SSDs, cheap flash drives). The move to ~30 nm dropped down P/E cycles to 5,000 and ~20 nm dropped it further to 3,000 (but yay for cheaper SSDs!). Planar TLC NAND actually varies from 500-1,500 P/E cycles, iirc. Granted, the move to 3D upped P/E cycles by ~3x. While you may have NAND capable of 1,000,000 P/E cycles right now, no one’s using them for $10-20 USB flash drives. Enterprise-level SAN or industrial applications, sure.
Granted, even at 1,000 P/E cycles, this is a non-concern for average users. 32GB * 1000 P/E cycles = 32 TB worth of NAND writes (not factoring write amplification). One would be more likely to lose the flash drive or have bought a bigger one before writing that much data to the drive.
Mind, I actually have killed a few flash drives running PortableApps due to excessive wear on specific cells (non-recoverable read/write errors). Guess wear leveling wasn’t particularly good on those drives.
thanks, I was getting worried about the earlier comment
One more utility for testing and debugging USB which wasn’t mentioned – USB test software eltima.com/products/usb-test-software/
I got writing errors using 2 programs. Are there any programs to fix my USB flash drive?
Hey, thanks a lot. useful tools, i’ve downloaded them all. Problem is, the drives I’m testing is 1TB large. 90 hours with “Check Flash”… 95 min with the RMPrepUPB– good advice
Again, thanks
Are you saying that is took 90 hours or so to test a 1 TB drive? Should I assume around 60 hours for a 64GB drive?
1TB is 1000 GB so 64 GB should take about 6 hrs
I made like 3 cycles on ready only mode with check flash and it didnt find any error, but in write and read test if found 48 errors, is it fake?
You can also try FakeFlashTest.exe as a very quick test for fake flash media.
Dear Raymod
Well Done for your useful article.
h2testw is kinda slow especially takes long while if you have very large size drives. Personally I used HDDScan to test usb flash.
I used the h2testw on 128GB, 1TB, and a 2TB flash drive. USB 2.0 metal keys configurations from China.
Ran over 100 hours, day and night.
It Loaded thousands of files onto the flash drive.
Read them back presumably.
Gave output drive size.
Close to as advertised.
I did a DEL *.h2t to get rid of all those files. ThAT HAPPENED IN A FLASH.
i need this tools
thanks.
thank you very nice
Thanks, it works.
Thanks Raymond. You rock.
Nice tool Raymond.
There’s more easy way to do that using the same OS API calls that will be used by any file manager tool should you happen to be needing to copy/write something on your USB drive. To do that you have to the following.
1. Select Start+R type cmd to start command prompt
2. In the command prompt window type:
fsutil file createnew X:\\dummy.dmp Y
where X is the drive letter for your USB stick,
Y is the number of kilobytes you want to write to your dummy.dmp file. Like if you want the file to be of 1 megabyte size type 1048576 instead of Y here (1 Mbyte=1024*1024=1048576 bytes)
If utility will fail to write this file, it may indicate you have problems with addressing or microchip on your USB drive.
thanks Ray. nice tool.