If the idea person isn’t going to be a part of the team I would actually be hesitant to give them any/much equity. But that the depends on the idea. Trivial ideas are a dime a dozen, but some ideas require deep knowledge about specific fields of industry, in such a case the idea is worth more.
Also, what is your relationship with the idea originator? Friendships are worth more than equity.
Anyway, I would probably give no more than 10% for just the idea. If the idea person wants more I would try to get them involved in the company or simply not start the company. There are a ton of great ideas to be had.
By the way, every time I tell someone I’m an app developer they say they have a great idea for an app. I rode with one cab driver the other day who said he had an idea for an app and “it’s like Uber but with one difference, but if I tell you you’ll steal it and become a billionaire”. Sure pal, good luck with that.
Edit: spelling
That was a joke by the way, but a half hearted truth into saying ideas are worthless, it’s execution that’s important.
Also - typically you see a technical and non-technical founders the non-technical will take on anything they are capable of doing - e.g. marketing, or at least managing the marketing (doing it too initially)
If you’re just giving an idea and are then hands off, I’d maybe give you 5% equity. Maybe.
If they don't like this, just take the idea and start the company without them if it's a good idea. A person with an idea that cannot execute on it has no leverage.
I don't know why you would be generous with this person. They will have no risk and no skin in the game, so why give them a big reward?
It wasn't so much "let's start a company" but more, hey here's an idea, if it takes off, throw me some equity.
Folks also love to say “execution is everything.”
Keep in mind, this idea tends to favor capital and insitutionalized power.
Executing a bad idea isn’t valuable and can cost you lots of money, time and opportunity.
Since most companies fail to make a profit, I suppose we could argue that most execution is worthless too.
So ideas can be seen as an exponent of sorts. An idea with a greater than 0 value will be useful for a team that can execute. Execution being equal, ideas are everything.
But not only that, the people and contexts that create great ideas are even more valueable.
Creativity is a resource that is always needed.
Uncreative people don’t like this at all, so they often try to devalue the power of ideas.
Of course they are also the ones who will try to execute on them.
Smart people understand the value of both. They also understand their own worth. They don’t need to devalue or belittle others in order to create partnerships.
There are plenty of brilliant idea generators who are paid handsomely simply for generating ideas and licensing them to existing companies.