Calculator for total install size of library

[AbeKline]

I would like a new calculator tool which can sum up the size on disk/download size of every game in my library.
I think it shouldn't be too complicated (though may be resource intensive, not a DB wizard). Every game has a list of depots which report both download and disk sizes.

The reason I want this is so I can figure out how feasible it would be for me to setup a LanCache with my entire library preloaded, then downsize my boot SSDs.

Thanks for your consideration