When formatting a USB drive or hard disk using the usual Windows OS tools, there is a field in the menu "Cluster size"... Typically, the user will skip this field and leave it at the default. Also, the reason for this may be that there is no hint as to how to correctly set this parameter.
If you open the formatting window and select the NTFS file system, then in the cluster size field, options in the range from 512 bytes to 64 KB become available. 
Let's see how the parameter affects "Cluster size" to work a flash drive. By definition, a cluster is the minimum space allocated to store a file. To make the best choice when formatting a device to NTFS, there are several criteria to consider.
You will need this instruction when formatting a removable storage device to NTFS.
Criterion 1: File sizes
Decide what size files you are going to store on the flash drive.
For example, the cluster size on a flash drive is 4096 bytes. If you copy a file of 1 byte, then it will still take 4096 bytes on the flash drive. Therefore, for small files, it is better to use a smaller cluster size. If the flash drive is intended for storing and viewing video and audio files, then it is better to choose a larger cluster size, somewhere around 32 or 64 kb. When the flash drive is intended for different purposes, then you can leave the default value.
Remember that an incorrectly selected cluster size leads to a loss of space on the flash drive. The system sets the standard cluster size to 4 KB. And if there are 10 thousand documents on the disk, 100 bytes each, then the loss will amount to 46 MB. If you formatted a USB flash drive with a cluster parameter of 32 kb, and the text document will be only 4 kb. It will still take 32 kb. This leads to irrational use of the flash drive and the loss of part of the space on it.
Microsoft uses the formula to calculate wasted space:
(cluster size) / 2 * (number of files)
Criterion 2: Desired communication speed
Consider the fact that the speed of data exchange on your drive depends on the size of the cluster. The larger the cluster, the fewer operations are performed when accessing the drive and the higher the speed of the flash drive. A movie recorded on a USB flash drive with a cluster size of 4 KB will play slower than on a drive with a cluster size of 64 KB.
Criterion 3: Reliability
Please note that a flash drive formatted with larger clusters is more reliable in use. Reduces the number of accesses to the media. Indeed, it is safer to send a piece of information in one large piece than several times in small pieces. 
Keep in mind that with non-standard cluster sizes, there may be problems with software that works with disks. These are mostly utilities that use defragmentation, which only works on standard clusters. When creating bootable USB drives, the cluster size must also be left as standard. By the way, our instructions will help you to complete this task.
Some users on the forums advise that when the size of a flash drive is more than 16 GB, divide it into 2 volumes and format them differently. A smaller volume should be formatted with a cluster parameter of 4 KB, and another for large files under 16-32 KB. Thus, both space optimization and the required performance will be achieved when viewing and recording large files.
So, the correct selection of the cluster size:
- allows you to effectively place data on a USB flash drive;
- speeds up the exchange of data on the storage medium when reading and writing;
- increases the reliability of the media.
And if you find it difficult to choose a cluster when formatting, then it is better to leave it as standard. You can also write about it in the comments. We will try to help you with the choice.
The main task of formatting a hard disk or flash drive is to select the correct cluster in the process of carrying out this procedure. There are several options and in each case you need to know what size is right for you to store large or small files.
The formatting process itself begins with the fact that Windows OS offers the user a regular, standard dialog, in which it is necessary to select the size of the cluster.
Naturally, many uninitiated people do not know the nuances of this procedure and set the "Default" item, which, in principle, is the right step if you are not sure of the correctness of your choice.
But at the same time, there are other options, and there is not a single hint on how to do it right. Therefore, first you need to figure out what file systems Windows offers:
NTFS clusters ranging in size from 512 to 64 KB;
FAT only one option - 64 KB;
FAT32 clusters from 1024 to 32 KB;
exFAT - maximum range, supports options from 512 bytes to 32768 KB or 32 MB. 
What size should I choose?
If you are not sure about the correct choice of your option, then in this case you first need to decide what files you plan to store on your media. If it is video, MP3 files and the like, then in this case you need to select the maximum cluster size. If these are small files, then feel free to choose the minimum size.
What does cluster size affect?
In fact, a cluster is the minimum volume that is allocated on the media for certain files. To make the selection principle more understandable, you need to understand what the cluster size itself affects. 
For example, you have a small file that is only 1 byte in size and the cluster size on disk is 4096 bytes. The saved file will occupy 4096 bytes of free space on the media. If such a file is transferred to a medium with a 512-byte cluster, then, naturally, it will take up much less space.
In other words, numerous small files will take up minimal space on media that have a cluster size of 512 bytes and vice versa. But at the same time, large clusters make information input and output operations much faster, which, as a result, will affect the reading and writing of files. 
A cluster size of 32 Kb or more will be appropriate if your media will store large files. At the same time, for any flash drive, the optimal cluster size is only 4 KB or less.
Remember this when formatting. But this rule only applies if you use a USB flash drive to transfer and store small files.
Finally, it is worth noting that if you are not sure of the correctness of the choice, then you can always use the magic button "Default". It is safe to say that this is the golden mean and you will no longer have to hesitate.
In the process of formatting a hard drive, flash drive or SD card, the user is prompted to select the size of the cluster when formatting and immediately determine the required type of file system. You can find out the cluster size from the report of the standard Windows defragmenter.
By definition, a cluster is considered the minimum amount of memory required for one document. The memory is divided into cells, in which the data will then be located. An important step is to determine the size of the sector; the number of cells for recording a file will depend on this. For example, the capacity of a cell is 4096 bytes, and the file being written is 300 bytes. In this case, the file will occupy the entire sector. A file weighing already 4000 bytes will also take up the entire sector.
Determining the volume of the sector
The standard cluster size directly depends on the selected file system:
- FAT32 ranges from 1024 bytes to 32 kb;
- NTFS cluster size (NTFS) from 512 bytes to 64 kb;
- FAT is always 64 kb and is not popular with users;
- exFAT with cluster size ranges from 512 bytes to 32 MB.
To correctly determine the capacity of the cell, it is necessary to determine in advance what data will be stored on the carrier, what is its type and volume. For photos, videos, or music, it is preferable to select the maximum cell size. If the disk will be used for documents, then it is recommended to opt for a small volume.
If you are in doubt as to which cluster size to choose when formatting, it is recommended that you leave the initially suggested default value.
The speed of the media is primarily affected by the cluster size. The smaller the volume, the more operations are performed by the system, and the slower the speed of writing or deleting data. In other words, the speed of work determines the size of the sector: the larger it is, the faster the medium works.
Formatting a disk is slightly different from a USB stick. If you are formatting data on a USB flash drive, then it is better to leave the system and cell size as is.
Damage and recovery of clusters
Due to a voltage drop or a factory defect, bad sectors of the hard drive appear, so from time to time it is recommended to check the HDD for damaged cells, and if they are found, to restore them.
To restore broken sectors, you can use the Victoria program, HDDRegenerator or the standard Skandisk utility. Cluster recovery:
- We open "My Computer".
- In the menu of the required disk, select "Properties".
- Find the "Service" section and click "Run Check".
- In the window that appears, select "Check and Repair", then click "Start".
Prevention and care
Occasionally, carrying out such procedures, you can significantly increase the life of the information carrier:
- monitor disk space, delete unnecessary files manually or using special programs;
- detect errors in the early stages by testing the disk with system utilities in time;
- split the hard drive into several sections;
- don't forget to back up important files.
Avoid mechanical damage and do not neglect defragmentation from time to time.
When formatting a disk or flash drive, you probably noticed that the system prompts you to select the size of the so-called "cluster". Its size varies depending on the type of file system on the disk. For example, for NTFS, the minimum cluster size is 512 Bytes, and the maximum is 64 KB. For FAT32 - from 4 to 64 KB. Often there are many options available to choose from, which can present an unprepared user with a logical question: what cluster size to choose when formatting a flash drive, disk or any other drive?
What is cluster size
Cluster, English) is a block in which the system will record information on your drive. The entire disk (flash drive) consists of a large array of these blocks, each of which contains a certain amount of data. The cluster size does not affect disk space, but it can affect how the system handles files on your media and how efficiently it uses the space available to it.
What cluster size to choose
You will hardly notice the difference with the naked eye when using different cluster sizes, but this parameter still affects the performance of the file system. When choosing a cluster size, it all depends on what you will be using the media for. If you will be saving a lot of small files, then it is better to reduce the cluster size so that the system does not waste space. If the content of the disk consists mainly of huge files, then you can increase the size of the cluster, which will increase performance, since Windows will make fewer calls to cells.
A simple example will help you understand this better:
If you have a 3KB file and the cluster size is 4KB, then the file will take the whole cluster or cell. This means that 1 KB free space will be lost. No other files can be written to the wasted space, so the space is actually wasted. On 10 such files, the loss will already be 10 KB, for 100 - 100 KB, for 1000 - 1000 KB, and so on. In this case, it is better to use a cluster size of 512 bytes or 1 KB, since the file will take six or three clusters without fragmentation and will not waste disk cells. This increases the efficiency of storing information, but at the same time decreases performance, since the system needs to perform more block accesses.
In today's world, the size of drives is getting larger and larger, and with it the size of the cluster plays a smaller and smaller role. Based on this, a universal solution would be to use the default cluster size settings and not change them. Of course, if you are a meticulous user who wants to do everything as it should and according to the manual, then proceed from the fact that for large files we use a large cluster size, and for small ones - a small one. But again, you won't notice much difference, unless you store tens and hundreds of thousands of 2-3 KB files on your flash drives or hard drives.
How to find out the cluster size of a disk or flash drive
A simple command at the command line will let you know what cluster size is being used on the disk connected to the computer. Note: You need an account with Administrator rights to run this command. If your profile does not have these rights, the system will ask you to enter the Administrator password.
Now you know what the cluster size is for and what principle to proceed from when formatting a disk or flash drive.
How do I determine the size of a cluster?
The master's answer:
If you have delved into the study of operating systems at least once, you will certainly come across the word "cluster", which means a very definite value, which is the size of a particular cell where files are stored. This size is directly proportional to the storage media.
So, if you are wondering what the size of the clusters - the cells on the hard disk - is, then apart from Windows OS and your own patience, you will not need anything else.
It is known that this value is formed in a quite definite way. Its size during hard disk formatting is set by the program itself, which has the same algorithms for each of the utilities involved. For example, a storage medium with a volume of no more than 1GB, clusters - up to 1Kb, respectively, a 4GB medium - 4Kb, and so on.
But it is not always worth believing the data in the pivot tables of the formatter. When converting from file systems, the cluster will have the size that is standard for the resulting file system. For example, if a hard disk is converted from a FAT32 system to an NTFS system, the volume of cells storing information is 512 bytes.
You can determine the cluster size using several methods without using additional software. And this method can be called manipulation to check the status of the defragmentation process of partitions - system, etc. To do this, open the menu of the "Start" button, go to the "Control Panel". A window will open in which double-click to open the "Administration" icon.
A window will appear again, in which there will be a shortcut "Computer Management" and now open the "Data Storage" section. This block allows you to start the "Disk Defragmenter" process, which is what you need to do.
Now activate the "Analysis" button and, after a couple of moments, the scanning of the selected partition in the hard disk will start in automatic mode. Then click the "Display report" icon, which will give you the opportunity to view in detail the information on the state of your hard disk in the highlighted window, where there is a line "Cluster size". In this example, the required value is 4Kb, and, accordingly, the system partition has a volume of about 12GB.
To save the found information about the section, click the "Save As" icon. A window will open where you will need to select the save directory, now name the file you are saving and confirm your action with the Enter key.
