Windows CMD Tool

Compact OS — Compress the OS to Free Up Disk Space

Compact OS runs Windows directly from compressed files, saving between 2.75 GB and 4.75 GB without deleting files or impacting performance on SSDs. Can be enabled or disabled at any time from CMD.

SystemWindows 10 / 11

Typical savings2.75 GB – 4.75 GB

PrivilegesAdministrator

Case 1 — Check current status

From running Windows (CMD as Administrator)

Compact.exe /CompactOS:Query

From WinPE — replace E:\Windows with the correct path

Compact.exe /CompactOS:Query /WinDir:E:\Windows

Case 2 — Enable / Disable Compact OS

Enable — Windows runs from compressed files (recommended on SSDs)

Compact.exe /CompactOS:always

Disable — reverts to uncompressed state

Compact.exe /CompactOS:never

Case 3 — Apply compressed image with DISM (WinPE / deployment)

Applies install.wim directly in compact mode when installing Windows

DISM /Apply-Image /ImageFile:install.wim /Index:1 /ApplyDir:D:\ /compact

Case 4 — Clean and export offline image with DISM

Mount image

Dism /Mount-Image /ImageFile:"C:\Images\install.wim" /Index:1 /MountDir:C:\mount\Windows

Clean up superseded components (may take several minutes)

Dism /Cleanup-Image /Image=C:\mount\Windows /StartComponentCleanup /ResetBase

Unmount and commit changes

Dism /Unmount-Image /MountDir:C:\mount\Windows /Commit

Export to new optimized file

Dism /Export-Image /SourceImageFile:C:\Images\install.wim /SourceIndex:1 /DestinationImageFile:C:\Images\install_cleaned.wim

Case 5 — Shrink hiberfil.sys (additional savings)

Reduce by 30% — keeps hibernation active

powercfg /h /type reduced

Remove completely — disables hibernation and saves ~1.5 GB on 4 GB RAM systems

powercfg /h off

Compact OS optimal on SSD · Not recommended on rotational HDD

Microsoft Docs