What is a .esd file?
Windows Electronic Software Download Image · Disk image · Microsoft · 2013 (Windows 8.1 era)
An .esd file is a highly compressed Windows image, the download-optimised sibling of .wim. Windows Update and the Media Creation Tool ship the OS as install.esd to save bandwidth.
What is a .esd file used for?
ESD uses the same WIM container with solid LZMS compression, making it roughly 30 percent smaller than a normal WIM, but read-only for servicing: you cannot mount and edit an ESD the way you can a WIM. Images downloaded from Microsoft may additionally be encrypted.
The practical task is nearly always conversion: deployment tools and some ISO builders want install.wim, so admins export the .esd to .wim with DISM before customising.
What opens a .esd file?
The .esd format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- DISM (export/apply)
- 7-Zip (recent versions)
macOS
- wimlib
Linux
- wimlib (wimlib-imagex)
Open a .esd file step by step
- Confirm the file really is a .esd. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with DISM (export/apply) or 7-Zip (recent versions).
- On Mac, use wimlib.
- On Linux, try wimlib (wimlib-imagex).
- Still stuck? Convert the .esd to wim, which opens more widely.
Why can't I open my .esd file?
Almost always because no installed app understands ESD. 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 .esd 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 .esd file
You can convert a .esd file to wim, iso (rebuild media) using a conversion tool or the export menu of an app that opens it.
What is the .esd file signature (magic bytes)?
A .esd file starts with the hex bytes 4D 53 57 49 4D 00 00 00, which read as MSWIM... in ASCII. Programs identify ESD by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for ESD. 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... | WIM container (MSWIM), solid-compressed |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .esd file?
An .esd file is a highly compressed Windows image, the download-optimised sibling of .wim. Windows Update and the Media Creation Tool ship the OS as install.esd to save bandwidth.
How do I convert install.esd to install.wim?
dism /Export-Image /SourceImageFile:install.esd /SourceIndex:1 /DestinationImageFile:install.wim /Compress:max. Pick the index of the edition you need first with /Get-WimInfo.
Why is the .esd so much smaller than a .wim?
Solid LZMS compression: files are compressed together in large blocks. The cost is that the image becomes read-only for mounting and servicing.
Can I delete C:\$WINDOWS.~BT or leftover .esd files?
After a successful upgrade, Disk Cleanup / Storage Sense can remove old setup files including downloaded ESDs. Do not delete them mid-upgrade.
Related formats
Sources
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