Unit Calculator- does an app like this already exist/ would it even be useful?

Consider the following extremely well thought out mockup:

https://imgur.com/IB6qDkh

Pretty amazing right? Does something like this already exist? (Tell you how many villagers for how much production of x unit)?

Would it be useful? It seems easy enough - but I figure I may be making some massive oversights on complexity. If even just supplying a good base line, though, it seems alright.