This is one of the most frequent questions I get about the startup world, and Chris Michel covers it well in this F|R interview, so I’m quoting here:

Typically VPs of early-stage companies get between 1 percent and 1.7 percent of a company. That’s just the benchmark, but it’s what investors will expect to see. The equity structure of a VC-backed company looks like this: The investors own 40 percent; the founder(s) own 40 percent; 20 percent is set aside in an employee option pool. After a round of additional funding, your senior managers may each be diluted from 1.5 percent to 0.75 percent. If you sell the company for $100 million — a very good outcome for a startup — the managers each get $750,000. If you toiled away for five years to build the company, is that worth giving up five years of a great salary? Maybe not.