Limit the space taken up by installing Windows by enabling Compact OS, a feature that lets you run the operating system from compressed files.
Natively, an installation of Windows 10 or Windows 11 occupies between 12 and 15 GB of storage space on a hard disk. Unfortunately, this amount of space can quickly become problematic on some modestly configured machines, on which the amount of storage offered is often limited.
For these machines, Microsoft has offered a feature since Windows 10 to run the operating system from compressed files. This function, Compact OS, thus makes it possible to compress certain Windows kernel files without this preventing the execution of the OS and having any impact on your documents or the applications installed on your machine.
By activating it on your PC, you will be able to save several gigabytes of space on your storage, both on Windows 10 and on Windows 11. The manipulation, which is done in command lines, is not insurmountable and is reversible. So you can easily go back if you change your mind.
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1. Check if Compact OS is already active
Before throwing yourself headlong into the activation of Compact OS, check if the option has not already been activated on the machine. To do this, right-click on the Start menu and open the Windows Terminal in administrator mode.
Then enter the following command and validate by pressing the Enter key on the keyboard:
compact /compactos:query
The Windows Terminal should then tell you whether the system is in the compact state or not.
2. Activate Compact OS
To activate the compression of Windows kernel files, still in the Terminal window, type the following command and validate by pressing the Enter key on the keyboard:
compact /compactos:always
The compression of the operating system files should then start, with the cursor displayed at the end of the line starting to spin. Take your pain in patience, the operation can last several minutes.
Once the compression is complete, the Terminal should display a message saying Completed compressing OS binaries along with the compression ratio performed.
3. Disable Compact OS
The compression of Windows kernel files is perfectly reversible, so it is possible to go back very easily, by entering a simple command line in the Terminal.
To deactivate Compact OS on your machine, run the following command and validate with the Enter key on the keyboard:
compact /compactos:never
The decompression process then starts and will take several minutes to complete, without affecting your files or applications installed on your PC.