Every step visible
Each calculator shows you exactly how the number was reached — formula, substitution, and result — so you can verify it yourself or hand it to someone who needs to check your work.
Built for the self-employed, contractors, and small business
Show your math.
Every calculator shows its work, cites its sources, and gives you a number you can send to your accountant.
60+ free calculators for self-employment tax, quarterly estimates, contractor pricing, invoicing, and more — each one with transparent step-by-step math.
The differentiator
Super calculators that compose.
Every other calc site has 50 individual tools. ShowMath has the chained-context layer — fill your profile once and these super calcs combine 4–6 primitives into one end-to-end answer with every step visible.
- Contractor profit engineChains 5
- Complete fitness planChains 5
- Freelancer tax masterChains 4
- Wealth trajectoryChains 5
- Home affordability masterChains 5
- Real estate investment chainChains 4
Citations on every formula
IRS publications, state statutes, standard industry rates. Every number is sourced. You know where it comes from before you use it.
Free forever for core calcs
Self-employment tax, quarterly estimates, rate math, invoice pricing — the tools contractors and freelancers reach for most often cost nothing.
Most-used tools
The calcs contractors reach for most.
Numbers you can stand behind.
Every calculator in the library shows its work. Cite it, screenshot it, send it. The math is documented so you don’t have to explain it.
Open the calculator library