WIMBoot or Windows Image Boot explained

Users slammed Microsoft Surface tablet over glaring disk space consumption issue. They believed, that the device’s operating system, ARM-compatible version of Windows called Windows RT consumed a little more than half of the on-board storage space available to the 32GB model, doling out only 15GB for files and application data. The situation was not very different on the 64GB model. Maximum 45GB was allotted! Consequently, an interesting disk space-saving technique WIMBoot, – a new deployment option, was introduced with the new Windows 8.1 Update.

Windows Image Boot (WIMBoot)

If Windows is deployed using this new technique on a device with 16GB or 32GB SSDs or eMMC storage, Microsoft says that it would leave over 12GB of free space. Earlier installation methods resulted in just 7GB of user-free space. The new deployment option, available for UEFI systems, called Windows Image Boot (or WIMBoot), follows a different approach than traditional Windows installations.

WIMBoot is a full set of OS files that come installed on a special partition on the storage device and compressed. Any Windows user mulling over the idea of shrinking Windows 8.1 down to size, enough for an OS to consume moderate amount of storage on tablets should find the WIMBoot option viable.

Unlike archaic install processes involving extraction of compressed Windows files from an image (WIM), WIMBoot keeps them compressed but when accessed, files are readily uncompressed. Since the .WIM install file is Read-only, it can also be used as a ‘factory-fresh’ restore image. Before that, the operating system needs to be installed via manual process, and is not yet supported by Microsoft’s deployment tools like WDS, MDT, and System Center Configuration Manager.

The installation makes it mandatory for users to copy the WIM file into a separate “images” partition (just like you would do for a Recovery image), then use DISM to create pointer files from the standard C: operating system volume into the WIM file. Windows knows how to boot the operating system (keeping all the files in the WIM) when configured in this setup. Here’s a screen-shot showing you how the disc looks like behind the scenes.

Windows Image Boot (WIMBoot)

Thus, a user can notice the amount of storage space the OS consumes, leaving the rest for apps and data. As expected, devices with WIMBoot are subject to a performance hit. Hence, it only targets new computers with small SSD or eMMC-based hard drives.

In all, you can get a full version of the OS while still having scope for the installations of apps and other programs. All important links to WIMBoot installation process are highlighted on the Windows Blog.

This post shows how to compact Windows 10 or Turn off Compact OS feature.

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Anand Khanse is the Admin of TheWindowsClub.com, a 10-year Microsoft MVP Awardee in Windows (2006-16) & a Windows Insider MVP. Please read the entire post & the comments first, create a System Restore Point before making any changes to your system & be careful about any 3rd-party offers while installing freeware.


  1. Anyone tried the software called ZIPmagic? I hear it’s DoubleSpace component doubles your SSD capacity by utilizing this WIMboot technology in WIndows 8.1.1…

  2. That is correct. ZIPmagic’s DoubleSpace works as advertised. It also does not require you to manually create Windows PE environments, WIM images, drop to the command line, or anything of the sort. In fact, you won’t even need external storage to convert your computer to WIMBoot (although, if you are recompressing a disk that you previously compressed – only then you will need it – DoubleSpace does support recompressing a previously compressed disk, again with WIMBoot). Please feel free to contact me directly (I am the author) for any feedback and questions. I hope you enjoy using DoubleSpace as much as I enjoyed building it!

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