Methodology: How We Build & Verify Every Calculator

1. Editorial Policy

CalcWorker publishes educational tools and explainers, not personalized financial, tax, legal, or medical advice. Our editorial commitments:

• Accuracy over speed: no calculator or article ships until its formulas have been verified against an authoritative source.
• No fabricated figures: we publish only rates, thresholds, and statistics we can cite. Annually adjusted figures (tax brackets, FICA wage caps) are labeled with their source and year.
• Public corrections: errors reported to support@calcworker.com are verified, fixed, and noted on the affected page.
• Independence: related-tool recommendations are chosen by topical relevance only. We accept no payment to feature, rank, or prioritize any tool, and advertising never influences calculation logic.

2. Calculation Verification Process

Every calculator passes through the same four-stage pipeline before it reaches you:

• Stage 1 — Formula sourcing. We start from the authoritative definition of the calculation: IRS publications for tax and withholding tools, standard monthly-compounding amortization for lending tools, Mifflin-St Jeor and WHO classifications for health tools, and published marketplace fee schedules for e-commerce tools.
• Stage 2 — Client-side implementation. Each engine is hand-written, audited vanilla JavaScript executed 100% in your browser. There is no server-side computation, no database, and no telemetry — your inputs never leave your device.
• Stage 3 — Benchmark testing. Outputs are checked against worked examples from the source publications and cross-checked with independent reference calculators. Edge cases (zero inputs, extreme values) are tested for sane behavior.
• Stage 4 — Review & release. The internal engineering team at Zaviyan LLC reviews every tool for mathematical correctness before production deployment. We do not ship unreviewed, auto-generated calculation logic.

3. Sources We Use

We cite primary authorities, not secondhand blog posts. Key sources by category:

• Tax & payroll tools: IRS.gov — Publication 15-T (Federal Income Tax Withholding Methods), Form W-4 guidance, and statutory FICA rates (6.2% Social Security up to the annual wage cap, 1.45% Medicare, 0.9% Additional Medicare).
• Mortgage & real estate tools: Consumer Financial Protection Bureau (CFPB) disclosures and standard amortization formulas used across the US mortgage industry (Fannie Mae / Freddie Mac conventions, PITI modeling).
• Health & fitness tools: the peer-reviewed Mifflin-St Jeor equation for Total Daily Energy Expenditure (TDEE) and World Health Organization (WHO) adult BMI classifications.
• Economic reference data: Federal Reserve statistical releases and Bureau of Labor Statistics series where tools reference inflation or cost-of-living figures.
• Marketplace fee tools: the official published fee schedules of Amazon, Etsy, eBay, and Shopify, updated when platforms announce changes.

4. Update Cadence

Rates, brackets, and fee structures change — our baselines change with them. Tax-year-dependent tools are reviewed each year for new IRS inflation adjustments; marketplace fee tools are updated when platforms publish new schedules; and every tool page carries a "Last updated" stamp so you can see how current its baseline is. Tax tool pages additionally carry a sources line linking directly to IRS.gov for independent verification.

5. Limitations — What Our Calculators Are Not

• Estimates, not advice: results are mathematical estimates for planning and education. They are not financial, tax, legal, or medical advice, and they do not create a professional-client relationship.
• Simplified models: real-world outcomes depend on individual circumstances our models intentionally simplify (local tax rules, lender-specific fees, personal health factors).
• Verify before deciding: for high-stakes decisions — filing taxes, signing a mortgage, making medical choices — confirm results with the cited primary source or a licensed professional.

Questions about our methods or a specific formula? Contact us at support@calcworker.com. Read more about who we are on our About page.