Regardless of level, you have to charge 2.5-3x to make up for the additional taxes you're paying, the benefits (health insurance, etc) you now have to pay full price for, and the inevitable gaps between contracts where you won't be making any money. Whether that bill rate is attainable varies depending on your skills, market, etc., but if you can't get that rate, then you're probably financially better off at the hypothetical fulltime job.