Rename file extensions including in all subfolders

How to recursively rename file extensions – i.e. rename file extensions including in all subfolders in Windows

This tip is great if you for example want to batch rename all .mkv files to .mp4 files (please backup your files before testing any of these methods, just in case).

If you want to rename files from one extension to another, recursively in all sub folders, then you can use this command in Windows Command Prompt:

forfiles /S /M *.ext1 /C “cmd /c rename @file @fname.ext2”

So for example, if you wanted to rename all mkv files to mp4 files, the command would be like this:

forfiles /S /M *.mkv /C “cmd /c rename @file @fname.mp4”

I hope this tip helps. It sure did for me when batch renaming lots of files. Tested in Windows 10 but works in older versions as well.

Good luck with your file extension changes!

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