What's missing from your freelance rate calculator?

I built ChargeWhat to solve a problem: freelancers massively undercharging because they forgot to account for self-employment tax, health insurance, and the fact that you can't bill every hour you work.

The calculator works backwards from your target take-home pay and accounts for SE tax (15.3% on 92.35% of net profit), your state income tax across all 50 states, realistic billable hours, business expenses, health insurance, and a profit buffer for slow months.

If you're a freelancer, I'd love for you to run your numbers and tell me what's missing or what doesn't match your real-world experience. A few things I'm curious about:

• Does the SE tax calculation feel accurate to what you actually pay?

• Are there expense categories you wish were included?

• Is there anything about how you set your rate that the calculator doesn't capture?

Any feedback welcome — brutal honesty appreciated.