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How to check if a MicroSD / SD card is fake

MicroSD cards, as well as SD cards, are used as a de-facto standard in any electronic device for the purpose of increasing their storage capacity. They are practically indispensable 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 stick.

The microSD become 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 among the best-selling and indispensable accessories. On these pages we have one complete guide for choosing and purchasing a microSD card.

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

How to tell if a true or fake microSD card

In an attempt to make the cards more attractive, some sellers reproduce known brands to perfection aesthetically. In addition to representing real fakes, these microSD cards often have one storage capacity which does not correspond to that explicitly indicated on the package.

In addition to the ability, another feature with which the end user is tried to deceive speed of writing and reading 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 to those write / read speeds.

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The biggest problem is that of data corruption on the microSD. Exploited to the end, a microSD that is not original, will inevitably lead to data corruption which will become illegible because the writing takes place in occupied memory areas. You may only notice a fake product when it's too late (and you've lost or permanently corrupted your data).

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

We want to clarify that this is a verification that can be done only afterwards, having the product in hand 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 originality of the SD card.

What programs to use to check if an original MicroSD card

To understand if it is false, once we get hold of the card, we must rely on software specially created for this purpose.

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

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The real capacity of a flash memory (like a microSD / SD) can only be verified by writing a file completely to fill all the available space and then reread it and check 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 addition to performing the operation described above automatically, is that of also providing us with important information regarding the writing and reading speed that normally they are asymmetric operations (i.e. writing slower than reading). At that point we could evaluate if the specifications stated they are true.


It is important to start from the completely empty or just formatted card. Carrying out the verification with the data already present on the board, in fact, although theoretically possible, very discouraged because if you were with a clearly fake (false) microSD, the result of the operation could compromise all the data already present.

This is exactly what happens when the original product is not used: it works until we fully exploit the declared capacity or until we write in corrupt memory areas.

H2testw (Windows)

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H2testw a reliable tool, used for years to check the originality of flash memories. It also works perfectly for testing USB sticks. It is a very slow program because it writes on all the memory space available and read back what he wrote (1GB at a time) without using particular precautions used instead on modern programs to complete the test in less time. Obviously the speed also depends on that of the SD card being tested.

  1. download the archive and extract the tool
  2. insert the microSD card into the computer
  3. run h2testw.exe
  4. choose English
  5. click on 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 and reading speeds.

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Test result: h2testw

If the test was successful and the card is original and fully functional, the output will be Test finished without errors. You can now delete all the .h2w files that the program created on the card during the test. If the test shows different results, it means that the card is corrupt and not original.

FakeFlashTest (Windows)

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The program FakeFlashTest present in the RMPrepUSB suite of tools. Compared to H2testw, optimized and built 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 different ways; allows a fast test indicated with Quick Size Test which writes 512 bytes of data at intervals and in different memory areas and a second precise test in terms of results, indicated with Test Empty Space (Slow) practically equal to 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 the computer
  3. run FAKEFLASHTEST.exe
  4. from the menu choose the letter that corresponds to the card in the computer
  5. click on Quick Size Test for the quick test or on Test Empty Space for the slowest but most reliable test
  6. wait for the end of the test

Test result: FakeFlashTest

In case of a positive outcome, the word PASSED will be present. In all other cases an error will be presented and the card you are testing is false.

F3X: Fight Flash Fraud (macOS)

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

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

<img class = "lazy lazy-hidden aligncenter size-full wp-image-39047" data-lazy-type = "image" src = " /microsd-falsa-f3x-ok.png” alt=”f3x positive result” width=”600″ height=”368″ data-lazy-/>

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

Test result: F3X

The message shown on success Success! Your card is ok !. You can delete the .h2w files used by the program for verification. If the message is different or there are errors, the length you have chosen to check for fake.

F3 (Linux)

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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 writing and then with reading. During these phases, the speed of the write and read operations will be indicated.

  1. unpack the archive
  2. enter the directory with the cd command
  3. compiled with the make command
  4. insert the microSD card into the computer
  5. mount the card (if you don't use the automount)
  6. run ./f3writecartellamount to start the writing process
  7. at the end of the writing process, run ./f3read cartellamount
  8. wait for the process to be completed

Test result: F3

If everything went well, at the end of the reading operation you should find the writing Data LOST: 0.00 Byte (0 sectors). You can delete the .h2w files created during the verification phase. In case of problems, the damage will be different and will indicate that the card is a non-original product.

What to do if the non-original MicroSD card

If the card is not original, our advice is obviously to immediately contact the seller or the site from which you placed the order. Ask for the refund complete, demonstrate through screenshots the tests you have done and also say that their product is clearly a fake and does not have the specifications indicated 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, as appropriate) to help other less aware users to decide whether or not to complete the purchase (see also next paragraph).

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If you really cannot return the card because it is very old or because the seller / shop refuses to consent to your request, a possible solution is to reprogram the card controller in order to respect the real capacity (many 128GB cards have 16GB capacity ). It is a different procedure which is outside the scope of this article. If you are interested we can make one in this regard to correct the capacity of a microSD (comment at the bottom of this article).

Purchase original MicroSD / SD cards

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

Having received the order, therefore, always proceed to the tests shown in this article to verify the originality of the card.

Read comments is reviews of other users who have purchased before you for greater security and before completing the order. Rely on guides on best microSD cards like ours or reliable and safe foreign sellers.