Use the Compact OS function to reduce the size of Windows 10 OS

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Windows 10 contains a new feature called Compact OS. With the built-in tool compact.exe, you can reduce the size of the operating system and run it from compressed files, as in WIMBoot. This article talks about the Compact OS function under Windows 10 and explains how to compress operating system files to save disk space.

Before talking about the compact functionality of Windows 10, let’s take a quick look at the WIMBoot functionality of Windows 8.1, which was introduced in Windows 8.1 to allow users to save space on devices with less memory. Windows 8.1 as such requires about 9 GB. When users implement WIMBoot, the disk space occupied is reduced to 3 GB.

WIMBoot means Windows Image Boot. Instead of decompressing all files in the operating system, it decompresses the files as needed and then compresses them into the INSTALL.WIM file. The Install.wim file has a size of about 3 GB and offers a lot of space to save. With this method, you do not need a recovery file because the WIMBoot file (Install.wim) is used to restructure the operating system if necessary.

Windows 10 Compact OS Function

The WIMBoot function described above was made to Windows 10 with some changes. Even better, under Windows 10, you don’t need a separate recovery file for a system reset. This will free up about 6 GB of storage space for your applications and software.

Operating system files are present and you will see that the operating system creates restore points at regular intervals or before downloading Windows 10 updates. System recovery points take up space.

Windows 10 requires about 3.x GB of disk space when compressed. Suppose 1 GB is allocated for system recovery. This way, the operating system takes up a little more space. It is good that under Windows 10, you can define the disk space you want to reserve for system recovery. So, if Windows 10 compact is 3 GB and you have configured 1 GB for system recovery, the total operating system disk space will be 4 GB + paging file space.

You can set the exchange file with System > Advanced Properties to know exactly how much disk space the operating system uses.
Windows 10 updates that occupy disk space are also installed regularly. So 4.x GB for OS combined with restore points and a paging file and one or two other GB for updates. Nevertheless, Windows 10’s compact operating system saves you about 4 GB – including swap files, system restore points and Windows updates.

Read related: system compression and how Windows 10 saves space on devices.

Reduce the size of the Windows 10 operating system

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You can compress the Windows 10 operating system during or after installation. There are many ways to compress Windows 10. I mention two simple methods below.


This command helps you compress the operating system while you install it. First, format the hard disk and partition it as you wish. Then apply the image file with the DISM :

DISM.exe /Apply-Image /ImageFile : Install. WIM /Index : 1 /Application : C : /COMPACT:ON

Once the image is applied to drive C, use the BCDBOOT command to specify the bootable partition:


Then reboot the computer to compress the operating system.

Using the COMPACT

You can use the Compact.exe command if you already have Windows 10 installed on your computer. To enable Windows 10 system compression, type the following command :

Compact / CompactOS : Always

Disable the Compact OS function under Windows 10

With the’Compact’ command, you can simply disable the Compact function until you need it again. Use the following syntax :

Compact / CompactOS : Never

The Compact OS function under Windows 10 is simple, as you can see. Note that it may take up to 20-30 minutes to execute the COMPACT command to compress or decompress the files.

For more information – such as using the’Compact’ function in scripts – see TechNet and MSDN.

Read more: CompactGUI compresses installed programs and saves storage space under Windows 10.

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