IMG is another kind of file format like ISO. Software distribution and installation medium available in IMG file format. Also, it is the best way to dump or rip CDs and DVDs in Windows and Mac to archive them. In this guide, let me show how to convert IMG to ISO in Windows OS.
Technically, we do not need to convert the IMG files in Windows 10/11 and the latest server Operating Systems because they can be mounted without any tools natively. But you may need to convert it to ISO in older versions such as Windows 7; also, if you need to attach any OS (or bootable) IMG disk image files to virtualisation software such as VMware, VirtualBox and Hyper-V because some of the virtualization software may not read the IMG file like ISO.
Few Tools Claimed to Convert IMG to ISO
PowerISO
This is a proper ISO and disk management tool available to download. Though it has a free version to download and install, PowerISO can convert only up to 300MB of data from IMG to ISO. If the IMG file is larger than 300MB, then it is not going to work.

imgtoiso
This is another free tool that possibly converts an IMG file to ISO, to be honest, I’m not sure whether it is working properly. Some say it only changes the file extension in the Windows OS platform. When I tried to convert a 4GB IMG file to ISO by this tool, it quickly converted the file, but guess what? I got only 350KB of the file as below.

Hence, I do not believe this tool can do a good job.
The Free Tool Worked for me to Convert IMG to ISO in Windows OS
OSFMount is a free and lightweight tool I found that can do the job well. It is easy to install and convert the IMG file to ISO in Windows 10 or 8.1.
1) Visit this site and download the application.
2) Make sure you have the administrative privilege to install this app. Once it is installed properly, open OSFMount.
3) Mount the IMG file here. Browse and attach it below. Click Next.

4) It will find the content and partitions inside this image file. Since we will not mount the specific partition, we will mount the entire image by selecting the 2nd option.

5) Mostly, you do not need to change any settings on the next screen; press the Mount.

6) Once the file is mounted inside OSFMount, right-click on the device and select “save to image”

7) Here, you will find a few types of image formats. Select ISO as a file type and give a name.

8) The process of converting IMG to ISO will begin. Depending on the file size and the processing power of your computer, it may take some time.
A successful message will appear once it is converted properly. Comparing and matching the file size of the output and input files will give some idea of proper conversion. I got almost the same size of IMG file as ISO.
Now the converted ISO file can be easily mounted by any ISO mounting software or attached to virtual machines to use.
Great, Thanks! Only working solution I found after hours of search.