How to convert bootable USB into an ISO file

Converting an ISO into a bootable USB or DVD is fairly easy.

The following apply when doing this conversion:

.iso to USB:

Use software like http://www.isotousb.com and the steps are simple.

.iso to DVD: 

Use software like ImgBurn.

What’s less familiar, hence the reason for this blog post, is how to convert a bootable USB to an .iso image file for later re-use.

The instructions for USB to .iso are as follows (for a Windows 7 installation for example):

1. Install ImgBurn. You can even get a portable version of it, just search for it.
2. Plug the bootable USB into the computer
3. Start ImgBurn.
4. Click on the “Create image file from files / folders” button on the home menu.
5. In “Sources” browse to the USB drive.
6. In “Destination” choose where to save the final .iso image.
7. Go to the “Advanced” tab on the right and then “Bootable Disk”.
8. Check the box “Make Bootable Image” and then, in the “Boot image” box browse to file “etfsboot.com” that is in the USB stick found in the folder “boot”.
9. In the field “Developer ID” put “Microsoft Corporation” and enter “07C0” in the “Load Segment” field.
10. Enter ‘4’ in the ‘Sectors To Load’ field if your etfsboot.com file is 2K is size, enter ‘8’ if it’s 4K. In other words, x = size of etfsboot.com in bytes / 512.
11. Click “Build” and you’re done!