How it's worked out
First the revenue: your take-home income grossed up for taxes, plus business costs (software, equipment, insurance, accounting). Then the hours: working weeks × hours per week × the share you can bill — admin, sales and learning aren't paid by clients.
rate = (income ÷ (1 − tax) + costs) ÷ (weeks × hours × billable share)
46 weeks leaves room for holidays and sick days. If your billable share is lower than you think, the rate goes up fast — tracking time on every task is the only way to know it.