I owned a business that had a shop rate for the purpose of pricing out jobs. You are correct, and there are other costs to employ people like FICA, vacation time, workman's comp and so on. The rule of thumb at the time, 20 years ago, was you multiply a person's hourly wage by 1.3 to get close to your actual cost. Then you need to mark it up. I'd wager that number has grown. Another complication is, the more experienced they are, the older they are and the more their health insurance costs you.