Create Windows Installer on Flash Disk with cmd

[theSEMAR]

Preparation:

1. Your OS is Windows 7 or 8
2. Flashdisk minimum size 4 GB
3. Windows 7 or 8 Installer image (usually with *.iso extension)
4. Windows 7 may use winrar, daemon tools, or other apps to open iso file, Windows 8 just open it from File Explorer
5. 1 cup of coffee or tea...  

Step by step:

1. Boot your Windows
2. Plug your flashdisk on USB port
3. Open Command Prompt run As Administrator
4. Command Prompt window will open, then type DISKPART
5. type LIST DISK, that will display like this,

DISKPART> list disk

 Disk ###  Status         Size     Free     Dyn  Gpt
 --------  -------------  -------  -------  ---  ---
 Disk 0    Online          149 GB   493 MB
 Disk 1    Online         3853 MB      0 B

Showing that my flashdisk is disk 1, if you have more than one harddisk, may be your flashdisk is named disk 2, disk 3 or so on. See the column size will let you know name of your flashdisk.

6. type SELECT DISK X

note: x is number of your flash disk, in this example i will type SELECT DISK 1

7. type CLEAN

note: your data in flash disk will be erased, make sure you have copy of your data in other place before do this step.

8. type CREATE PARTITION PRIMARY
9. type ACTIVE
10. type FORMAT QUICK

you already create bootable flashdisk wich can used to booting from BIOS. Command Prompt window can be closed.

11. open your windows installer iso image file.
12. Copy all files inside iso image to your flashdisk.
13. Drink your coffee or tea, done...  

[theSEMAR]

Update: This method also can be used on Windows 10.

[theSEMAR]

Update:
....
2. Flashdisk minimum size 4 GB
....

Because recent Windows 10 64-bit ISOs have size more than 4 GB, a flashdisk with size of 8 GB or more is needed to make a Windows installer.

[theSEMAR]

Update:

Starting from Windows 10 1909 (19H2) 64-bit, there is a file in an ISO that have size more than 4 GB.
Because of that, the default format of diskpart (FAT32) cannot accept the file. You should format flashdisk with NTFS to make Windows installer.
The steps are all the same except when performing the format command (last step).
Here are the complete steps: (don't forget to run CMD as administrator)

C:\Windows\system32>diskpart

DISKPART> list disk

Disk ###  Status         Size     Free     Dyn  Gpt
--------  -------------  -------  -------  ---  ---
Disk 0    Online          149 GB  493 MB
Disk 1    Online         7706 MB    0 B

DISKPART> select disk 1

ATTENTION!!! WARNING!!!
If you have more than 1 HDD, it will be Disk 0, Disk 1, Disk 2, Disk 3 and so on.
Make sure you select correct disk (your flashdisk) by seeing it size before doing "clean" command.

DISKPART> clean

DISKPART> create partition primary

DISKPART> active

DISKPART> format fs=ntfs quick

Done.

Now you can copy-paste all files inside Windows ISO (by open it in File Explorer) to your flashdisk.

[Moe]

Keep in mind that UEFI cannot boot NTFS or ExFAT, which creates an interesting issue as you have noted.

You need to format your flash drive FAT in order to boot, but FAT won't accommodate the installer image.

So you still need to create both a FAT and an NTFS/ExFAT partition on the flash. The FAT just needs to handle the initial boot and then kick things over to the NTFA/ExFAT partition to handle the rest.

Rufus can handle all that for you. Just download the ISO from Microsoft and it'll take care of making the necessary partitions.


Additional note: if you go this route, you will need to disable secure boot, because Microsoft.

[theSEMAR]

Oh yea...?, thanks @Moe for detailed explanation.

FYI, currently I don't have PC/laptop with secure boot features because most of my hardwares are ~10 years old. So, I only tested my bootable NTFS flashdisk on that hardwares (and sucessfull installing Windows).

I usually only use Rufus for create linux or bsd installer.

I will try your method if in the future i have devices wich have secure boot features.
Once again, thanks.

Cheers. 

[Moe]

It is more a UEFI vs legacy BIOS. Ironically, older machines using BIOS won't have issues with NTFS boot media. UEFI does. Go figure.