Tools
Free tools
Small calculators for the money side of a one-person business. Figures come from official pages and are dated on each tool.
- Self-employment tax calculator (2026)
Schedule SE from your net profit: Social Security, Medicare, the 0.9% Additional Medicare Tax, the deductible half and a quarterly set-aside.
- Digital product fee calculator
What one sale leaves you on Stripe, PayPal, Gumroad, Lemon Squeezy, Payhip and Stripe Managed Payments, and who handles sales tax.
- Solo 401(k) and SEP IRA contribution calculator (2026)
The most a sole proprietor can contribute to each plan for 2026, with catch-up and day-job deferrals.
Estimates for planning only, not licensed advice. Calculations run in your browser; nothing you enter is sent anywhere.