Preparing quotes, finding clients and doing admin take time even though they never appear on an invoice. Your rate should spread your annual target over the hours you can actually charge for.
An example with numbers
You work 40 hours a week for 46 weeks and can bill 60% of them. That is 1,104 billable hours. To bring in $55,200 before costs and taxes you would need to charge $50 an hour.
Try it with your numbers
Try the same target with two different shares of non-billable time. See how much the rate changes even though you work the same hours.
Example figures for learning purposes. They are not a recommendation and do not replace professional advice.