Is there a way to automatically calculate my entire library storage needs?

[Animehunter2k16]

Hi
I'm thinking of backing up my entire library collection and was hoping there was a way to automatically calculate how big an HDD size I need to store them.

I found the method of selecting everything in my library and selecting install games, but all it tells is, there's not enough space. It doesn't give you a total of the storage needed.

Thanks