Interesting. When I was younger (just starting out) I didn't have much idea of how much markup others had when I was working for them (as employee or contractor). I typically thought it might be 20-25% markup. And... in some cases I know it's that, but that has tended to be the low end. It's usually more like minimum 50% markup; if you're getting $50/hr from an agency, they're charging at least $75/hr, probably more. If you're getting $60/hr, they're probably charging at least $90/hr, and so on.