What is the best exFAT allocation unit size in 2024, and how do you set it? exFAT (Extended File Allocation Table) is a file system commonly used on external storage devices like USB drives and SD cards. The Allocation Unit Size (AUS) is the smallest unit of data storage in a file system and affects both file storage efficiency and device performance. Choosing the appropriate allocation unit size is crucial for optimizing the performance of an exFAT-formatted device in 2024. Here are some common allocation unit sizes and recommendations for setting them: 1. For most users, the recommended exFAT allocation unit size is 4096 bytes (4KB). This provides a good balance between speed and space utilization. 2. If you primarily store large files (like high-definition videos or substantial software), consider using 64KB or 128KB allocation unit sizes. This can reduce file fragmentation and improve read/write speeds, but might waste some disk space. 3. For smaller devices or scenarios where space optimization is crucial, you can choose 512 bytes or 1024 bytes (1KB) allocation unit sizes. However, this might result in slower write speeds and increased fragmentation. 4. The method to set the exFAT allocation unit size in 2024 depends on your operating system. On Windows, you can select the allocation unit size when formatting through the "Disk Management" tool. On macOS, you can do this in "Disk Utility." In Linux or other systems, you can use command-line like `mkfs.exfat` and specify the `-s` or `--cluster-size` parameter. Remember that changing the allocation unit size will erase your device, so ensure you back up important data before proceeding. Choose the most suitable allocation unit size based on your specific needs to achieve optimal performance and efficiency.

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What is the Suitable Allocation Unit Size for exFAT?
Change exFAT Allocation Unit Size with Tool - Partition Master - Easier
Change exFAT Allocation Unit Size with CMD
Why Set exFAT Allocation Unit Size?

The exFAT (Extended File Allocation Table) file system is specifically optimized for flash memory, like SD cards and USB flash drives. However, users often get confused when choosing the ideal exFAT allocation unit size. This typically happens when users attempt to create or format an exFAT drive using various disk management tools.

So, today we will discuss the best exFAT allocation unit size. After reading through its requirements, precise units, etc., you will be able to change the allocation unit size by the end of this article. There will also be a quick FAQ section to answer any questions you might have.

What is the appropriate allocation unit size for exFAT?

A cluster is the smallest unit of disk space that can be allocated for storing a file. Thus, a single file can occupy one cluster, and a file can span multiple clusters depending on its size and the cluster size. So, if a file's actual size exceeds a single cluster, it will occupy multiple clusters; if the actual file size is less than the cluster size, it will still occupy at least one cluster. Now, what happens if you set the wrong exFAT allocation unit size?

Ideal exFAT allocation unit size:

Storing small files in large clusters leads to wasted space. Conversely, storing large files in partitions with small clusters can degrade read/write performance, because the file will be fragmented across many clusters, requiring more time to collect.

Can I use the default exFAT partition size?

Of course, if the user has no insight into the relationship between cluster size and performance for their particular use case, exFAT's default allocation unit size might be a good choice; it automatically selects the best cluster size based on the volume capacity.

This is why it's easy to understand the ideal exFAT allocation unit size for different users. Now, let's proceed with the steps to set this size.

For more information about allocation unit size, such as the best SSD cluster size, refer to the following article:

What is the Best SSD Allocation Unit Size in Windows 11/10

On this page, we will introduce what is the best SSD allocation unit size in Windows 11/10. You can also find the best solution to change it.

How to Change exFAT Allocation Unit Size - 2 Effective Ways

After figuring out the best allocation unit size for exFAT, users might need to change it on their system based on the file size. The following quick steps can easily modify this size. There are mainly two methods to change and reset the exFAT allocation unit size:

Method 1: Change exFAT Allocation Unit Size with Partition Master Tool

When looking for the best way to change exFAT allocation unit size, you can easily opt for a dedicated partition management tool like Partition Master Professional. It's perfect for individual users who want to manage different disk partitions or copy data to another HDD or SSD. It runs smoothly on Windows Vista, 7, 8, 8.1, 10, and 11.

Step 1: Right click on the partition whose cluster size you want to change, select “Advanced” and then click “Change Cluster Size”.

Right click to change cluster size:

Step 2: Click on the “Size List” under “New Size”, select the cluster size of the disk partition you want to resize, and then click “OK”.

Step 3: Click “Execute 1 Task(s)” and then click “Apply” to confirm.

Figure 12-12. Changing cluster size

When it comes to changing the exFAT allocation unit size, tools Partition Master is a perfect choice as it safely manages hard drives for beginners. It helps users with disk partition management, offering services like delete disk partition, wipe partition data, hide or unhide partitions, and more. Users can enjoy basic features with the free version or upgrade to the paid version based on immediate needs.

Features of the Partition Master tool:

allocation unit size of FAT32

Next, I'll guide you through opening Diskpart and using commands to change the exFAT allocation unit size in CMD. Be cautious when typing commands to avoid errors or data loss.

Method 2: Change exFAT Allocation Unit Size via CMD

CMD (Command Prompt) is the command-line interpreter in the Windows operating system, used for managing disks and partitions along with various administrative operations. Therefore, the steps to quickly change the exFAT allocation unit size using CMD are as follows:

Step 1: In the Windows search bar, choose “Run as administrator.”

Step 2: Open the Command Prompt, type diskpart, and press “Enter.”

Step 3. Enter each of the following lines in turn, pressing “Enter” after each one.

list disk
select disk * (replace * with the target disk or partition number)
list partition
select partition * (replace * with the partition number)
format fs=exFAT unit=32k (the allocation unit size of 32k can be changed to a different value if desired)

Change exFAT allocation unit size with Diskpart

Appendix: Why the exFAT Partition Size Matters

exFAT is the best solution for dealing with large files, which cannot be managed by NTFS or FAT32. That's why you need to set the allocation unit size for exFAT. Here are some significant reasons to set this allocation unit size:

Avoiding wasted space: When creating or formatting a partition, the allocation unit size for exFAT is set to its default value. Users unaware of the significance of this setting may proceed, impacting space-saving on the system. Hence, setting the allocation unit size is crucial to avoid space issues on exFAT.
Improving read/write speed: The allocation unit or cluster size significantly affects disk performance or disk space utilization. Incorrect settings can lead to decreased disk read or write speeds. Therefore, setting the exFAT allocation unit size is necessary for optimizing partition efficiency.

exfat allocation unit size

Now that we've gone over the quick reasons to set the allocation unit size for exFAT, let's continue with the recommended sizes.

The bottom line?

Thus, it's easy to grasp what the best exFAT allocation unit size for a partition is – the smallest amount of storage required for any file on the partition. After you learn its relation to space saving and performance on the partition, it's a piece of cake to set the perfect exFAT allocation unit size.

Users can choose the allocation unit size based on file size or opt for the default setting in the exFAT file format. The allocation unit size for exFAT can be easily changed using tools like Partition Master or CDM. Users can follow a step-by-step guide to accurately set the optimal allocation unit size for exFAT in a quick manner.

Frequently Asked Questions (FAQ) About exFAT Allocation Unit Size

After getting familiar with the different allocation unit sizes for exFAT and the methods to set them, you might have some questions. Therefore, here are a few frequently asked questions that can provide quick assistance:

1. What is an allocation unit?

The allocation unit (AU) size is the smallest amount of sectors that can be allocated to a file within a partition. Therefore, it is the minimum amount of storage that can be allocated or deallocated to an ASM disk group.

What is the best allocation unit size for a 64GB exFAT drive?

For exFAT 64 GB, the optimal allocation unit size is 128 KB.

3. What allocation unit size should I use?

Users can choose the cluster size based on the file size. Microsoft's recommended default cluster size for exFAT is:

7MB - 256MB: 4KB
256MB - 32GB: 32KB
32GB - 256TB: 128KB

7MB - 256MB: 4KB
256MB - 32GB: 32KB
32GB - 256TB: 128KB

4. Can exFAT store more than 4GB?

Yes, exFAT is efficient for storing content larger than 4GB, as it offers excellent support for large files. It successfully overcomes the limitations of FAT32, which caps file size at 4GB and partition size at 8TB.

What is the best exFAT allocation unit size? [Setting Guide]