Methodology

How tools are built

Calculators are written in TypeScript as pure functions inside a shared package (@bedrocka-tools/calc), with Vitest unit tests that cover edge cases: zero-interest loans, negative-cash-flow companies, SBA fee bracket boundaries, and every published sample problem we can find from primary sources. The package has no UI and no side effects — if a calculator gives the wrong answer, there's one file to fix and a failing test that tells us it was wrong.

Formula sourcing — primary sources only

We only cite primary sources. Blog-of-a-blog-of-a-PDF is not a source. Primary sources we use routinely:

• SBA SOPs and Policy Notices (sba.gov) for SBA 7(a), 504, microloan, and export programs
• IRS Publications and the Internal Revenue Code (irs.gov) for tax treatment of interest, depreciation, and Section 179
• CFPB regulations and guidance (consumerfinance.gov) for Truth in Lending (Reg Z) and the APR formulas
• Federal Reserve H.15 release for Prime, Fed funds, Treasury yields
• Bureau of Labor Statistics (BLS) CPI and wage data for real-dollar adjustments
• SEC Edgar for public-company disclosure examples when we need a worked case

Secondary sources (industry benchmarks, whitepapers) are used only where a primary source does not exist — and always labeled as such. Bessemer's SaaS benchmarks, Paul Graham's essays on startup finance, and similar named analyses are cited by name with URL.

Review process

1. Draft: calculator logic and explanatory copy are drafted, sometimes AI-assisted, always with the primary source pulled up in parallel and every non-trivial number checked against it.
2. SME review: each calculator is reviewed by a named human with operator experience in the domain — for finance calculators, Byron Malone in his operator capacity, and for new tools outside that expertise we engage domain reviewers and credit them on the page.
3. Citation verification: every URL cited is spot-checked at publish time and every named rule or rate is re-checked against the source document.
4. Publish: with a Last updated stamp and a dateModified schema.org field on every page.

Update cadence

Every calculator is reviewed on a quarterly cadence. In addition, we update immediately on any of the following triggers:

• SBA issues a new SOP version or fee-schedule Notice
• The IRS publishes a new Section 179 / bonus depreciation limit
• A Federal Reserve rate change that affects Prime-indexed rates in our tools
• A new regulation that changes what counts as eligible collateral, income, or expense

Error reporting

If a calculator gives you the wrong answer, we want to hear. Email info@bedrockatools.com with the tool, the inputs you used, and the output you got. We respond to every report within 3 business days; if the tool is wrong, we fix it and publish a correction note on our corrections page.

Per-category methodology

Each calculator category has a dedicated methodology page covering the primary sources, formula derivations, edge cases, and update protocol specific to that category:

• Lending — business loans, SBA 7(a), equipment financing, invoice factoring.
• Operating finance — cash runway, customer economics, cap table, valuation, break-even, working capital.
• Pricing & margins — gross margin, retainer-to-hourly-rate.
• Real estate — DSCR and CRE underwriting.
• Tax & depreciation — quarterly estimated tax, R&D credit, payroll tax, self-employment tax.

Limitations

Calculators on this site are estimates for educational use. They do not account for every feature of every lender, every tax treatment in every state, or the specifics of your individual circumstances. They are not financial, investment, legal, or tax advice. Consult a licensed professional — a CPA, a banker, an attorney — for decisions with real dollars attached. The tools are designed to make you a better-informed buyer of professional advice, not a replacement for it.