Let's just say that you can even fall from 4 feet in the air and still get hurt. Um, I would say the highest you can probably go is... Wait, for all I know you could be attempting su!c!d3, never mind, not telling you. Keep it at that. But if you fall from 4 stories in the air, let's just say that if you're not d3@d, you're going to wish you were.
You have to define the options a lot better. A friend of mine fumbled and hit his head on a sidewalk and was killed instantly. Felix Baumgartner just jumped from a helium balloon from 24 miles up and landed fine.