How to Run Command Line Defrag on Windows 10?

Command line defrag on Windows 10 is no longer confusing once you read this article. Because, this time, you’ll learn much about defrag command on Windows 10 and how to execute the defragmentation on your own.


By Michael / Updated on May 12, 2023

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How to defrag disks with command lines on Windows 10?

“There’re different methods to defrag hard disks for PCs while using command lines is one of the solutions. Command Prompt is such a powerful tool for disk management that I want to give it a shot. However, I’m a complete computing novice and have no such experience which means I don’t know any parameters for defragmentation. Can anyone tell me how to perform disk defrag with command line?”.

Why defrag with command lines on Windows 10?

Before answering it, you should first know what disk defrag and command line are. Fragmentation occurs when pieces of a file get scattered throughout your hard disk which causes low write and read speed and thus, slow disk performance; defrag or defragmentation is going to reorganize those problematic files on a hard drive by putting the pieces back together and adjacent to each other. Defrag helps improve overall disk performance and in this case, it’s recommended to run disk defragmentation on a regular basis.

DiskPart is a Windows built-in utility for disk management and is one of the best choices for defragmentation. By inputting command lines in DiskPart, you can perform different defrag operations. Each command line or order has a distinctive function. More than defragmentation, DiskPart command line also helps with many other things including disk format and disk deletion.

The parameters of command line defrag on Windows 10

To perform any disk management operation on Windows 10, you must type corresponding parameters. Defragmentation is no exception either. There’re around 8 parameters you can use for disk defrag. Here, I put them in a chart and explained the meaning of each one.

Note: Be sure to run DiskPart as administrator.


 Meaning of different parameters


Specifies the drive letter or the mount point path of the volume to be defragmented or analyzed

defrag.exe -c

Use defrag.exe to defragment all volumes on your computer

defrag.exe c: -a

Use defrage.exe to analyze the C: drive

defrag.exe c: -r

Use defrage.exe to perform partial defragmentation which attempts to consolidate only the fragments that are smaller than 64MB.

defrag.exe c: -w

Use Defrage.exe to perform a full defragment

defrag.exe c: -f

Use defrage.exe to force the defragment even when the free space is less than 15% on the C partition

defrag.exe c: -v

Use defrage.exe to show detailed analysis and defragmentation output

Alternative to the command line for disk defrag

Command line defrag Windows 10 is a good and powerful way for disk defragmentation. However, it can be very challenging for novices to remember all the order lines, and even for those professional users, they must be extremely careful when making any changes.

So, why don’t you consider using other easier alternatives? Here’re 2 free programs that can help you run defragmentation in a more user-friendly way – Windows 10 built-in defragmenter and a third-party software utility AOMEI Partition Assistant Standard. In the following tutorial, you’ll learn to use both of them in the right way.

Method 1. Using Windows 10 built-in disk defragmenter

“Defragment and Optimize Drives” is a disk defrag feature that comes with Windows 10. With it, you can schedule defrag to let it run at intervals.


1. In the search box on the lower left of the desktop, type “defrag”.

2. Among the popup results, select “Defragment and Optimize Drives” to bring up the window of the Windows built-in defragmenter.

3. Select the target disk, hit “Change settings” to make a schedule.

4. Hit “Analyze” to see whether fragmentation is over 15%. If so, move on.

5. Click on “Optimize” to start the defragmentation.

Method 2. Using third-party disk manager utility

If you think the command line is too complex or the first method won’t work, maybe it’s time to turn to a third-party software utility for help. Here, I recommend AOMEI Partition Assistant Standard.  It’s a free disk management program containing a large number of useful features besides disk defrag including disk format, hard drive wiping, and SSD secure erase.

What’s the best alternative to command-line defrag on Windows 10? Try the most impressive third-party defragmenter to make everything easier!

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Step 1. Install and launch AOMEI Partition Assistant Standard. Then, right-click on the target disk and select “Disk Defrag” in the dropdown menu.

disk defrag

Step 2. Tick the target disk and hit “Analyze”.


Step 3. After the analysis is done, the disk will be scored in terms of its fragmentation rate.


Step 4. Launch the defragmentation by hitting the “Defrag” button.


It’ll take several minutes before the process is done and latter, the disk will be scored again.

Should I defrag an SSD with command lines?

partition alignment

Since SSD and HDD share different working principles, it's not advised to defrag an SSD with command lines. An SSD is able to read data scattered on different clusters as fast as read data on continuous clusters. Thus, defrag is meaningless for SSD. If you insist on defragging an SSD, then, you could cause unnecessary tear and wear and in return, the lifespan will get shortened.

So, how to boost up SSD performance without defragging it? Luckily, you can upgrade Partition Assistant to the Pro edition to enjoy the feature of SSD 4K alignment to get the most out of the hard disk.

Note: To make the disk defrag run at intervals, you can try the schedule defrag feature of the professional edition.


In this post, command line defrag on Windows 10 has been exhaustively introduced. You’ve learnt what it is, why you do it and how perform it. When it comes to the ways to defrag, there’re 2 alternatives to command line – Windows built-in defragmenter and a third-party disk management software utility AOMEI Partition Assistant. As for me, I prefer the later one since it’s more user-friendly, more complete, and much faster! If you want to use this software on Servers, please try its Server edition.

Michael · Staff Editor
Michael is a professinal editor of AOMEI editor team.