Simple marketing (planning) tool for indie hackers

When we, indiehackers, get an idea, we just want to jump right in. Sometimes, it makes sense to have a tool to measure viability of the idea at the get-go.

I typicaly run some back envelop calculations regarding profit target, duration, tax, expense, revenue and build several models on pricing vs volume.

So I spent little bit of time last night to build a simple tool that might benefit all of us here. Temporary link here: https://increnovation.azurewebsites.net/fermi

Disclaimer, it was late last night. It barely works and have plenty of room to improve. I have no plan to monetize this. More stuff to come such as add typical conversion rate, more charts and models etc etc...

So the asks:

1. useful?
2. any other numbers I should collect/calculate for useful insights?
3. advise in general

I think I should say it's marketing (planning) than a finance tool...