When you figure out your hourly rate, you need to include things like time off (since you can’t bill for time not worked for a client, but if you were an employee, you’d most likely get paid time off), sick time (similar), money that you want to set aside for retirement (many employers match their employees’ retirement plan contribution, and some even provide employer contributions regardless of employee contributions). You also have to account for taxes, since you’re on the hook for both employee and employer parts of payroll taxes (a.k.a. self-employment taxes). I’ve put all this into a formula for freelancers here.