Even assuming that this "screwed factor" is something meaningful, you miscalculated it. I think you're trying to find (percentage increase in work over normal hours/percentage increase in pay over normal pay).

If your pay is just a percentage of a company's profits, the amount of equity you hold has no impact on this number. If you working 50% more hours generates 10% more profits (or whatever) for the company, you get 10% more pay for 50% more work, so the screwed factor is 5.

Again, this is assuming that the screwed factor is meaningful in the context of a startup, and it isn't. First of all, the different possible outcomes for an early employee of a small startup can mostly be boiled down to two, maybe three: the startup IPOs and you get rich, it gets sold and you get well-compensated, it fails and you get nothing. Treating your income as a very smooth function of the hours you work is misguided in this kind of scenario.

Second, contributing to a culture of working really hard on the startup (by working overtime) might be more important than the work you actually do in your overtime. Startup employees don't work in a vacuum.

This is late and nobody will see this, but what the heck...

You are wrong for two reasons: 1. If you want more than 2%, than you need to start the company yourself. The only way anyone can over come your screwed factor is if they are a founder.

2. 2% of a successful company should make you relatively wealthy, thus negating your screwed factor.