I'm looking for software/tool for testing the integrity/capacity of a flash/SD card to check if it's a fake or not.

Preferably cross-platform, but can be OSX/*unix based also.

Arti­cles on flash card fraud:

  • 1
    There is no valuable data on the card, right? It can be entirely overwritten for test purposes. Or not?
    – Nicolas Raoul
    Commented Jul 24, 2014 at 10:37
  • 1
    No data, brand new. Just to make sure it's genuine.
    – kenorb
    Commented Jul 24, 2014 at 10:52
  • 1
    Please define 'fake': not 100% in working order (damaged areas), refurbished, not from the claimed manufacturer, not the claimed capacity, ...
    – user416
    Commented Jul 24, 2014 at 15:04
  • Fake in the meaning that the SD card doesn't work as genuine (as it's claimed). So it shows the wrong capacity, e.g. people selling 256GB SD cards (Kingston), but in real they're just 32GB No-name from China. The problem is that the system still show them as 256GB (which are not). And sometimes its life-time/speed is lowered/faked in comparision with genuine, so they stop working after writing some files. Please refer to the linked articles.
    – kenorb
    Commented Jul 24, 2014 at 16:57
  • 1
    This article describes how the memory cards are being manipulated: how it work with micro SD cards You can not be sure anymore, neither with brand names nor with reputable dealers.
    – Fred
    Commented Oct 24, 2019 at 21:46

3 Answers 3


I'm not sure if it's any good, but I was reading about this one earlier. Seems to be brand new. Looks promising in the screenshot the author provided.

True Capacity Screenshot

True Capacity is an open-source tool that checks flash drives and memory cards for a fake capacity. It's a Bash script, so it's not cross-platform; Linux only.

It performs 2 tests. Test 1 writes data and reports how much data was written. Test 2 reads data and reports how much data was read.

You can find release information here, and the latest download link. Installation instructions, a list of dependencies, and flash drive preparation instructions are in a text file included in the ZIP download. Make sure to read it, as you have to format your card correctly.

To launch the script:

bash /path/to/true-capacity-manager

When it completes you get an output listing an approximate real capacity. If the results of the tests are different, use the results from test 2.

  • 1
    The download link at mega.nz on the forum thread is dead.
    – kenorb
    Commented Jul 10, 2017 at 13:54

Found so far H2testw. In general, it's in German, but English execution is possible. Mainly it's for Windows, but there are the following alternatives:

  • F3 (Fight Flash Fraud) by Michel Machado - an alternative to h2testw (GitHub sources),

    Open source Linux software to test flash memory capacity.

  • F3X GUI for F3

  • sdspeed - SD Card Speed Test (GitHub sources),

    sdspeed - SD Memory Card Speed Test - Fight Flash Fraud

    Measures the effective read and write speed of SD memory cards. sdspeed runs on Mac OS X. sdspeed is based on F3 (see details below) but with some changes so that it was possible to write a native Mac OS X user interface based on it.

Read more:


You can use Chipgenius. Often this will reveal the true size of the memory chips(s) fitted by the manufacturer. It's floating around on many places on the Internet, but here is a (Russian) download site for many versions.
Some other programs on that site may be useful, but my Russian knowledge is limited to approx 10 days of study, years ago ;-)

This site also mentions a program called FakeFlashTest, I don't know it.

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