Windows Compact OS Saves Gigabytes With One Command

Windows Compact OS can reduce the amount of storage Windows uses by keeping system files compressed directly on the drive.

Microsoft has included Compact OS in Windows for years, but the feature recently gained attention again after users on Reddit highlighted how a single command can enable it.

Compact OS compresses Windows system files

Compact OS stores Windows system files in compressed form instead of keeping them uncompressed. Microsoft primarily designed the feature for PCs with limited storage and memory.

The feature works on both UEFI- and BIOS-based systems and doesn’t require any third-party software.

Microsoft provides the built-in Compact.exe utility for checking and controlling the feature. Users can open Command Prompt as administrator and run:

• Compact.exe /CompactOS:query to check the current Compact OS status.
• Compact.exe /CompactOS:always to enable Compact OS.
• Compact.exe /CompactOS:never to disable it and decompress Windows system files.

Compact OS can free several gigabytes

Microsoft’s older Windows 10 testing shows how much space Compact OS can potentially save.

On a Windows 10 x64 installation with 4GB of memory, Microsoft measured approximately 15.06GB of storage usage without Compact OS. Enabling the feature reduced that figure to around 11.3GB.

That represents savings of roughly 3.76GB, although the result on a modern Windows 11 PC will depend on the installation and system configuration.

Compact OS does come with a potential trade-off. Windows needs to decompress compressed system files when applications or system components access them, shifting some work away from storage and toward other system resources.

Users with plenty of free storage may have little reason to enable it, but Compact OS could prove useful on systems where every gigabyte matters.

In other Windows news, Microsoft is improving Windows code signing, while the company has also warned Edge users about the upcoming MDAG and WIP retirement.

Via Neowin