I realize this has been addressed in various forms before but I feel this case is unique.
How much equity would you give to a friend who came up with the idea for a startup but is voluntarily bowing out of a cofounder role (to be an advisor only)?
A friend of mine ("Sam") came up with a good idea for a startup. He brought me (the tech guy) and another guy he knows ("Eric", expert in the vertical) together to be cofounders. He's helped us negotiate a partnership/cofounder agreement (worked on legal docs), spoken with angels/VCs (has a lot of contacts there), and kept things moving as much as possible.
Sam is in a completely unrelated field (healthcare). He realizes he doesn't have the vertical knowledge or contacts, and isn't a tech guy. So he doesn't want to be cofounder. He just wants to help in any way possible. He's been working on the idea for about 5-6 months (not full time), probably 3 months or so with Sam before I came on.
So far this is just an idea, with some software I'm writing and no investment (not even seed). Sam's proposal for equity split is about 40% each for cofounders, and 15% for him as advisor.
My first reaction is that this is high compared to other advisor agreements. However, this situation is different since it was his idea originally and him bringing us together that made this happen.
vvvv Update vvvv
Currently the agreement is that Sam will be the first in line to get diluted as needed to carve out additional option pools for initial employees, strategic advisors, etc. When we get to a funding event we will see what the VCs have to say about current allocation and be prepared to adjust as necessary.
Food for thought - For comparison, here's an interesting guidepost: Accelerators like YC, AngelPad, Techstars, etc usually provide around $10K-20K of cash, physical space to work, access to experts and previous participants on a daily basis, and access to every VC and Angel in the Valley.
Their take? About 5-6%. I'm wondering (not rhetorically) how that compares to the work that Sam has done so far.