What is a .wim file?
Windows Imaging Format File · Disk image · Microsoft · 2007 (Windows Vista)
A .wim file is a Windows Imaging Format archive: a file-based disk image Microsoft uses to deploy Windows itself. The install.wim on installation media contains the entire operating system.
What is a .wim file used for?
WIM images are file-based rather than sector-based, so one archive can hold several Windows editions while storing every duplicate file once. Tools like DISM apply, mount and service them, and Windows Setup installs from them directly.
IT departments meet WIM constantly: capturing golden images, injecting drivers and updates offline, and building bootable media. 7-Zip opens a .wim like a folder, which makes extracting single files easy.
What opens a .wim file?
The .wim format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- DISM (mount/apply)
- 7-Zip
- Windows Setup
macOS
- 7-Zip via CLI ports
- wimlib
Linux
- wimlib (wimlib-imagex)
- 7-Zip
Open a .wim file step by step
- Confirm the file really is a .wim. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with DISM (mount/apply) or 7-Zip.
- On Mac, use 7-Zip via CLI ports or wimlib.
- On Linux, try wimlib (wimlib-imagex) or 7-Zip.
- Still stuck? Convert the .wim to esd (compress), which opens more widely.
Why can't I open my .wim file?
Almost always because no installed app understands WIM. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .wim at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .wim file
You can convert a .wim file to esd (compress), iso (rebuild media), vhd (apply to virtual disk) using a conversion tool or the export menu of an app that opens it.
What is the .wim file signature (magic bytes)?
A .wim file starts with the hex bytes 4D 53 57 49 4D 00 00 00, which read as MSWIM... in ASCII. Programs identify WIM by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for WIM. For a full breakdown, see the WIM file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 4D 53 57 49 4D 00 00 00 | 0 | MSWIM... | ASCII MSWIM |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .wim file?
A .wim file is a Windows Imaging Format archive: a file-based disk image Microsoft uses to deploy Windows itself. The install.wim on installation media contains the entire operating system.
How do I open a .wim file?
For a quick look, open it in 7-Zip. To work with it properly, mount it with DISM (dism /Mount-Wim) or wimlib, edit, then commit or discard the changes.
What is install.wim?
The core image on Windows installation media: it holds the complete OS, often multiple editions in one file. Setup applies it to your disk during installation.
How do I convert install.esd to install.wim?
Use DISM: dism /Export-Image with the source .esd, the index you want, and /Compress:max writes a standard .wim that deployment tools accept.
Related formats
Sources
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