Our Methodology

This page explains how CalcAuthority builds, documents, and maintains its calculator tools. Transparency about methods is a core principle: if you cannot see how a result was calculated, you cannot judge whether it applies to your situation.

The House Method

Every serious calculator on CalcAuthority is built to show five things, in order. This is the standard we hold new tools to, and the structure you will find on each calculator page:

  1. The formula — stated in plain language so you can reproduce the calculation by hand.
  2. The assumptions — what the tool takes as given, and what you must supply.
  3. Worked examples — at least two, with real numbers, so you can verify the tool.
  4. Verdict bands — where appropriate, plain-English ranges for reading the result.
  5. Limitations — what the estimate does not include and where it breaks down.

The policies below explain how we apply each part of that method.

Formula Policy

Where a standard, widely accepted formula exists — such as the amortization formula for loans and mortgages, or the percentage change formula — we use it exactly as established. We do not approximate or substitute proprietary methods. The formula is stated on each calculator page in plain language so any user can reproduce the calculation by hand.

For estimates with no single authoritative formula (such as take-home pay, which depends on individual tax variables), we use a simplified model, state the simplification explicitly, and note what is not included in the estimate.

Stated Assumptions

Every calculation involves assumptions. CalcAuthority states these directly on each calculator page rather than burying them in footnotes. Common examples:

  • Salary-to-hourly conversions assume a user-specified number of hours and weeks. The default (40 hours × 52 weeks) is stated, not silently applied.
  • Loan and mortgage calculations assume fixed interest rates and equal monthly payments. Variable-rate loans are not modeled.
  • Take-home pay estimates use a single combined effective deduction rate supplied by the user. They do not apply a tax-table calculation, which would require personal filing information.
  • Gas cost calculations use the MPG figure entered by the user, which may differ from the EPA sticker.

Worked Examples

Every calculator includes at least two worked numeric examples. These serve two purposes: they demonstrate the formula in action with real numbers, and they allow any user to verify that the calculator is functioning correctly by checking a known input/output pair. If the calculator and the worked example produce different results for the same inputs, that is a signal to investigate — please use the contact page to report it.

Benchmark & Source Policy

Some calculators reference typical ranges — for example, how large a labor burden usually runs, or what cash runway is considered safe. We are explicit about where these come from:

  • Where a figure is a published or standard value (a tax rate, a physical conversion constant, an amortization formula), we use it exactly and it is verifiable.
  • Where a range is an editorial rule of thumb — derived from how a formula behaves at typical inputs, or from general operating experience rather than a specific published survey — we label it as such on the page in a benchmark note. We do not dress up rules of thumb as statistics.
  • We do not fabricate citations. If a claim would require a source we cannot verify, we either remove the claim or mark it clearly as needing a source rather than inventing one.

Verdict-Band Policy

Many business calculators return a number that means little without context — a margin, a runway, a payback period. Where it helps, we add verdict bands: plain-English ranges that explain how to read the result ("under 3 months of runway is a danger zone," and so on). These bands are decision aids, not guarantees. They describe how much ordinary friction a result can absorb or what a figure typically signals — and every page tells you to calibrate against your own history, because your trade, market, and risk determine the honest thresholds. Bands are always presented as editorial judgment, never as a rule you must follow.

Update & Review Policy

Calculators and guides are reviewed for real-world usefulness and honest framing by Gerald G., Founder and Reviewing Editor, whose background is in the trades (journeyman cabinet installer, subcontractor, and former contracting business owner who operated with 18 employees). Contractor and trade tools draw on that field experience; general small-business tools rest on established formulas, stated in full, with Gerald as reviewing editor rather than a claimed authority beyond the trades.

We update pages when standard figures change materially — tax rates, FICA thresholds, FLSA overtime rules — and when we find a clearer way to present the math. Calculator logic is checked against the worked examples shown on each page. If you find a discrepancy between a calculator's output and its stated example, please report it via the Contact page.

Limitations of Each Estimate

Each calculator page includes a disclaimer section that specifies what the estimate does not include. For example:

  • Mortgage calculator results do not include property tax, insurance, PMI, or HOA fees.
  • Take-home pay results do not account for state-specific tax rules, multiple income sources, or complex deduction scenarios.
  • Loan payment results do not include origination fees, prepayment penalties, or other lender charges.

Stating these limitations is not a legal disclaimer only — it is essential for the estimate to be useful. A number without its limitations is easy to misapply.

Review and Accuracy

Formulas are verified against reference sources (textbooks, government publications, or established financial standards) and cross-checked with worked examples before publication. Calculator logic is tested against the worked examples shown on each page. If you find a discrepancy between a calculator's output and its stated worked example, please report it via the Contact page.

We update pages when regulatory thresholds, tax rates, or standard figures change materially — for example, FICA rates or FLSA overtime thresholds. If you notice outdated information, contact us.

What Our Calculators Are Not

CalcAuthority calculators are educational tools. They are not:

  • Financial advice
  • Tax advice or tax preparation tools
  • Mortgage or lending applications
  • Legal advice
  • Personalized professional recommendations

See our Financial Disclaimer for the full statement. For decisions that depend on accurate financial, tax, or legal outcomes, consult a qualified professional.