How to check if a MicroSD / SD card is fake

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Lluís Enric Mayans
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MicroSD cards, as well as SD cards, are used as a de-facto standard in any electronic device in order to increase its storage capacity. They are practically inthespensabili in modern cameras (both reflex and compact) and excellent accessories for smartphones, tablets, portable consoles (Nintendo Switch) or as “storage” to always carry with you, like a USB pen.

The microSD becomes SD through adapters often included in the packages and for this reason we will treat them in the same way.



The offers on microSD are therefore many because they are among the best-selling and inthespensable accessories. On these pages we have one complete guide for choosing and purchasing a microSD card.

In the constant search for offers, however, we must pay close attention because we could find ourselves buying a card at a price that is too advantageous to be real, especially (not always) if the offer comes from Chinese sites or anonymous sellers on ebay.

In an effort to make the cards more palatable, some vendors aesthetically reproduce well-known brands to perfection. In adthetion to representing real "fakes", these microSD cards often have one storage capacity which does not correspond to that explicitly inthecated on the package.

In adthetion to the ability, another feature that tries to fool the end user is the speed of writing and reatheng of a card. Many cards have higher prices because they guarantee very high speed (expressed in terms of MB / s). “Fake” cards often don't get up to those read / write speeds.

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The biggest problem, however, is that of data corruption on the microSD. Exploited to the full, a microSD that is not original will inevitably lead to data corruption that will become unreadable because writing takes place in occupied memory areas. You may only spot a fake product when it is already too late (and you have permanently lost or corrupted your data).



We will see in this article how to check if a microSD card has the capacity and speed of writing / reatheng inthecated by the real manufacturer; in other words we will be able to understand if the card microSD is fake or genuine.

We want to clarify that this is a verification that can only be done afterwards, having the product in the hands and therefore only after purchasing it. The checks that can be made from an aesthetic point of view in fact do not represent a guarantee of the originality of the SD card.

To understand if it is fake, once we get hold of the card, we have to rely on software created specifically for the purpose.

We absolutely cannot rely on what the computer's operating system shows us; both Windows and macOS (or Linux) get storage capacity information from the USB controller on card chips that can be programmed and altered at will.

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The real capacity of a flash memory (such as a microSD / SD) can only be verified by completely writing a file until it fills all the available space and then re-reatheng it and checking if it represents a 1: 1 copy of the original file.

To do this, we will show you some tools available for both Windows and Mac. The advantage of using these programs, in adthetion to performing the operation described above automatically, is to also provide us with important information regartheng speed. writing and reatheng which are normally asymmetric operations (ie writing is slower than reatheng). We could then evaluate whether the specifications declared correspond to the truth.



H2testw (Windows)

H2testw is a reliable tool, used for years to verify the originality of flash memories. It also works perfectly for testing USB sticks. It is a very slow program because it writes to all memory space available and reads back what he wrote again (1GB at a time) without using any special precautions used on modern programs to complete the test in less time. Of course, the speed also depends on the speed of the SD card you are testing.

  1. download the archive and extract the tool
  2. insert the microSD card into your computer
  3. run h2testw.exe
  4. choose "English"
  5. cliccate su “Select Target”
  6. choose the letter that corresponds to the card
  7. click on “Write + Verify”
  8. wait for the end of the process

During the test, you can also check the writing speed and the reatheng speed.

FakeFlashTest (Windows)

The program FakeFlashTest is present in the RMPrepUSB tool suite. Compared to H2testw, it is optimized and implemented in relatively modern times, so as to have a good execution speed and at the same time be very reliable for newly built flash memories.

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It works in two thefferent modes; allows a quick test inthecated with "Quick Size Test" which writes 512 bytes of data at thefferent intervals and in thefferent memory areas and a second precise test in terms of results, inthecated with Test Empty Space (Slow) practically the same as the test performed by H2testw . Be careful because the quick test overwrites whatever is in the memory you are testing.



  1. download the archive and extract the program
  2. insert the microSD card into your computer
  3. run FAKEFLASHTEST.exe
  4. from the menu, choose the letter that corresponds to the card in your computer
  5. click on “Quick Size Test” for the quick test or on “Test Empty Space” for the slower but reliable test
  6. wait for the end of the test

F3X: Fight Flash Fraud (macOS)

With F3X you can test the real capacity of the flash memory (so it also works for USB sticks) and the writing / reatheng speed.

  1. unpack the archive with the tool
  2. insert the microSD card into your computer
  3. start F3X.app
  4. select the card from the list
  5. click on "Start Test"
  6. wait for the outcome of the verification operation

You will notice the read / write speed during the test.

F3 (Linux)

The same program used on Mac but without a graphical interface, called F3. You will need to be familiar with the terminal. The tool performs the test in two phases: first we will proceed with the writing and then with the reatheng. During these phases, the speed of the write and read operation will be inthecated.

  1. unpack the archive
  2. enter the therectory with the command "cd"
  3. compiled with the "make" command
  4. insert the microSD card into your computer
  5. mount the card (if you don't use automount)
  6. execute “./f3write folderamount” to start the writing process
  7. at the end of the writing process, execute "./f3read folderamount"
  8. wait for the process to complete

If the card is not original, our advice is of course to immediately contact the seller or the site from which you placed your order. Ask for the reimbursement complete, demonstrate via screenshots the tests you have done and also say that their product is clearly a fake and does not have the specifications inthecated by the original manufacturer. In many cases, you will also have to ship the product back. With the checks you have made, however, always leave reviews (both positive and negative, depentheng on the case) to help other less aware users decide whether or not to complete the purchase (see also next paragraph).

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If you just can't return the card because it is very old or because the vendor / shop refuses to agree to your request, a possible solution is to reprogram the card controller to match the actual capacity (many 128GB cards have 16GB capacity. ). This is a thefferent procedure which is beyond the scope of this article. If you are interested we can do one about it to correct the capacity of a microSD (comment at the bottom of this article).

The advice is not so obvious: always rely on well-known sites and trusted sellers (with high ratings). It is not uncommon to find real matches of fake products that mix with perfectly original products.

Once the order has been received, always proceed to the tests listed in this article to verify the originality of the card.

Read Comments e reviews of other users who have purchased before you for greater security and before completing the order. Rely on guides on best microSD cards such as ours or reliable and safe overseas sellers.

How to check if a MicroSD / SD card is fake

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