Here, this article for Convert Firmware Zip to IPSW you can follow below Easy Steps and iOS firmware files arrive in IPSW file format and also users may download IPSW firmware file for iPhone or iPad and it arrives as a .zip file instead of .ipsw as expected, this usually on a Mac too.
This problem creates because of the web browser you used to download the IPSW firmware file which assigns it a ZIP archive extension that is easy to fix and to change an IPSW marked as a .zip file into IPSW .ipsw file that is the region for this. iTunes will not recognize a firmware as a .zip file as .ipsw file and must have the .ipsw file extension for it to be used by the iTunes software to be able to update iOS on an iPhone or iPad that is best.
Change .zip File to IPSW .ipsw File for Window
Step 1: You can show file extensions go Start Menu > Control Panel > Folder Options > View > and turn off Hide file extensions.
Step 2: Once you have file extensions visible on the computer.
Step 3: After, simply must rename the .zip file to the .ipsw file.
Step 4: Done, a .ipsw file will now be useful.
IPSW file with a .ipsw file extension you simply see below:
Step 1: Access a repository of iOS IPSW file downloads.
Step 2: After Find the IPSW file you wish.
Step 3: After then right click.
Step 4: Choose Save As on the link.
Step 5: After Save the IPSW file.
Step 6: Done.
Here, a .zip is a proper file format but for archives and .ipsw is also a proper file format but it’s for iOS firmware files and also the best thing for IPSW files are not supposed to be .zip archives and you can always download .ipsw files only from Apple servers.
Here, the complete guide for Convert Firmware Zip to IPSW Easy Steps and you read this guide very helpful for you.