Reduce the Size of install.wim

Latest versions of Windows 10 ISO contains WIM file that is big for FAT32 file system.

Files larger than 4GB can NOT be stored on a FAT32 partition. This is due to FAT32 limitation.

If you want to boot under UEFI firmware by utilizing NTFS file system you might fail, as not all UEFI systems are able to boot from external boot media using NTFS.

This tutorial will show you how to extract the needed edition from the original install.wim to get a smaller install.wim file.

1. Extract the required install.wim out of the ISO file or mount the ISO file.

2. Open the Command Prompt by typing cmd.exe into Start Menu, right-click on Cmd.exe, and open it as an administrator.

3. Execute the following DISM command with the correct path to the install.wim to get the index that represents needed Windows edition:


Dism /Get-WimInfo /WimFile:"E:\Sources\install.wim"

The output might look like the following:
Reduce the Size of install.wim   JFYQqpQ

4. Execute following command to create a "Mount" folder at root of C: partition.


Md C:\Mount

5. Extract the right index (6 in this case as I want to install Windows 10 Pro edition) into a new WIM file via DISM command:


Dism /Export-Image /SourceImageFile:"E:\sources\install.wim" /SourceIndex:6 /DestinationImageFile:"c:\Mount\install.wim

Reduce the Size of install.wim   2balxyu

Replace the "E:\sources\install.wim" path with correct path to the install.wim file.

It reduced the install.wim file size to only 3.80 GB which will now fits within the file size limitation of FAT32.

6. Copy newly created install.wim file stored within C:\Mount folder onto an already prepared USB stick with all the other needed files from the original ISO.