On: Ask HN: How much % for the Idea/Concepts behind a Startup

[cperciva]

But without the original idea, the start-up wouldn't come to formation to begin with, right?

Ideas are cheap. It's execution which matters.

Also the even split between the co-founders isn't quite possible either (one is working summer only, another is part time over summer).

Then estimate how much contribution each "co-founder" is making and allocate stock in proportion to that.