So how do you rename multiple file extensions at once? If you have a directory full of files that need to be changed from .PNG to .JPG, it’s going to take forever to do this using the method above. Luckily, there are a couple of different ways we can change the file extension for multiple files at once.
For those of you who are familiar with the command line, there is a very easy command you can use to perform very simple file renaming tasks. There are two commands that you can use at the command prompt: ren and rename. Both of them do the exact same thing, so it’s just a preference as to which one you use.
If you have a folder with a bunch of JPGs inside and you want to change the file extension to PNG, for example, you would type in the following command:
ren *.jpg *.png
As you can see above, the command changed all the files in that directory with a JPG file extension to ones with a PNG file extension. You can get more information on how to use the ren command from Microsoft’s website.