In this article, I will be talking about the CrystalDiskMark.

CrystalDiskMark storage test is some kind of stress test to assess the storage's speed. Hence, If you have past with failure warning signs about HDD, then I recommend not to run this tool.

Table of Contents

What is CrystalDiskMark?

CrystalDiskMark is a tool created by Crystal Dew World to test the SSD and HDD storage speed in different ways. It is mainly designed to give you an idea on your storage's speed like copying speed, reading speed, simultaneous reading speed, and many more.

You can get from here.

See in the image below how the interface looks like.

CrystalDiskMark Interface with SSD storage speed test result.
CrystalDiskMark Interface with SSD storage speed test result.

Furthermore, it's only available for Windows OS.

Interface of CrystalDiskMark

As you can see in the image placed above this section, there are 5 green buttons on the left side, 4 boxes to select the test parameters, and the result box placed at the center.

So, let's first go with 4 boxes that are basically the test parameters that you have to select.

  • The first option let you choose the Test Count - The number of tests that the tool should perform. It ranges from 1 to 9.
  • The second option allows you to select the Test Size. It ranges from 16MiB to 64000MiB.
  • The third option is for drive selection. It will list all of the identifiable storage drives on you machine. From the list, you have to select only one.
  • The fourth option is for unit selection. It gives you the 4 units to display the speed in. They are MB/s, GB/s, IOPS (Input Output per Seconds), and microseconds.

On the center of the screen, there two sections for displaying the Read and Write speeds.

So, If you click on the "All" button, then this tool will start performing all the tests. And, If you want to perform each test by manually then press the remaining green buttons after the previous test ends.

Interpretation of CrystalDiskMark Results

In the version of 7.0.0, there are 4 types of tests as follow.

  • SEQ1M Q8T1
  • SEQ1M Q1T1
  • RND4K Q32T16
  • RND4K Q1T1

Before I go into in detail about the different tests listed above, first understand what's the allocation of size.

So, when the data transaction happen between the operating system and a storage, it takes some time. Such transaction of data often termed as Input/Output Operations. And, how much input/output operations take place in a second is called IOPS.

Now, understanding of block size (allocation size) is becomes necessary here. Different operating systems have different sets of rules to allocate the size. And, the size of the one block determines the data that can be fitted in it.

Now consider the single notepad text file of 1KB in size and you want to save it.

So, creating a block of 4KB is much more economical than creating the 1MB size block. Because 4KB allocation size will prevent the storage from getting wasted. But, at the same time, it has its own drawback also.

Larger block provides higher data transfer rates compared to smaller block. And, that's what the CrystalDiskMark shows.


SEQ1M Q8T1 is interpreted as Sequential Test for 1 Mebibyte block size data with total of 8 tasks in sequence on thread 1.

Sequential speed represents the read and write speeds of the large files. Here, the large files are nothing but your movies, large Zip or any compressed file, and like.

As I said they are fast to copy due to large allocation size for the one data.

The Q8 shows that amount of task that CrystalDiskMark will perform a the same point. Here, take a breath and understand one concept. You computer cannot do 8 tasks at the same point in the storage.

As a result, it put the processes on the queue. So that the machine can easily remember and process it well. So, this test can be demanding but not when compared to RND4K Q32T16 test.

In addition to that, the processes in the queue will take fraction of second for data transaction to start. It's speed will always be higher than SEQ1M Q1T1.


It is interpreted as Sequential Test for 1 Mebibyte block size data with total of 1 task in sequence on thread 1.

It's as same as SEQ1M Q8T1. The difference here is in the number processes in the queue. The read and write speed readings of this test will always be less than SEQ1M Q1T1.

It shows the reading and writing speeds of one process in the queue.

RND4K Q32T16

It is interpreted as Random 4 Kibibyte Test for 32 processes in queue on 16 threads.

As per the interpretation, it will put massive load on the storage. In this SSD speed will perform far better than HDD. The poor speed results of HDD are due to its moving parts.

In this test, the tool will read and write data from different blocks of 4 kibibyte size with a almost 32 processes in parallel or series - thanks to the multi-threading. In practical, it's something like preview of video files in your PC which sometimes takes a time to load from hidden thumbnails folder. Some videos get it faster while some have to wait for it.


It is interpreted as Random 4 Kibibyte Test 1 Process in Queue on One Thread. Like SEQ1M Q1T1, it will perform RND4K test for one process in the queue on one thread.

It basically gives an information on how much time the single files of smaller takes when you try to read , copy, or move it.

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