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.
How to open 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. For a step-by-step walkthrough, see how to open a .esd file.
Windows
- DISM (export/apply)
- 7-Zip (recent versions)
macOS
- wimlib
Linux
- wimlib (wimlib-imagex)
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.
.esd file signature (magic bytes)
Programs recognise a .esd file by the bytes at the start of the file, not by its name. These are the signatures for ESD. For a full breakdown, see the ESD file signature page.
| Hex signature | Offset | Note |
|---|---|---|
| 4D 53 57 49 4D 00 00 00 | 0 | 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
Details on this page were checked against authoritative references: