Editorial approach & standards

Every calculator and article on this site follows a deliberate editorial process. I'm not running a content farm — I write content to be accurate and useful, not to hit keyword quotas. When a topic is contested or the math has been simplified, I say so explicitly. When my numbers conflict with a source, I dig in and fix it.

The editorial process for each calculator page follows these steps:

• Formula sourcing: The underlying formula or methodology is identified from its primary source — a government agency, academic institution, or professional standards body. For example, the BMI calculator uses the WHO classification criteria; the mortgage calculator uses standard amortization math validated against Federal Reserve publications; tax calculators reference current IRS schedules directly.
• Implementation verification: Each calculator's output is tested against known reference values. When an authoritative source publishes example calculations (as the IRS does for tax brackets, or the NIH does for BMR formulas), those examples are used as test cases.
• Educational content review: The explanatory text below each calculator is reviewed against the cited primary sources. Claims are attributed with numbered citations. When a formula has known limitations — such as BMI's poor accuracy for athletes — those limitations are stated clearly.
• Ongoing updates: Tax rates, contribution limits, and other time-sensitive data are reviewed and updated on a regular cycle. Each page carries a dateModified timestamp reflecting the most recent review.

Research methodology & source hierarchy

Content accuracy lives or dies on source quality. I follow a strict source hierarchy:

• Tier 1 — Government agencies and regulatory bodies: IRS publications, CDC clinical guidelines, NIH research databases (PubMed), USDA dietary references, HUD housing data, BLS labor statistics, DOL wage data, OSHA safety standards, USPTO filing guidelines, and the Federal Reserve's Survey of Consumer Finances.
• Tier 2 — Professional standards organizations: ASCE (structural engineering), SAE (automotive), NFPA/NEC (electrical), ASHRAE (HVAC), ASTM (materials), and IEEE (computing) — along with the AMA, AHA, and WHO for health-related content.
• Tier 3 — Peer-reviewed research: Published studies from journals indexed in PubMed, JSTOR, or Google Scholar. Used to support specific claims, provide context on formula limitations, and cite clinical evidence.
• Tier 4 — Industry data and expert consensus: Reports from AAA, Edmunds, Zillow, NAHB, and similar organizations. Used for benchmark data (average costs, typical ranges) but cross-referenced against government data when available.

Sources that do not meet these standards — forums, anonymous content, social media, and AI-generated text — are not used as references.

Areas of focus

Building 500+ calculators means I've spent a lot of time in places most people don't — IRS publications, engineering handbooks, clinical research papers. That knowledge comes from doing the research, not from claiming credentials I don't have. Here's how it breaks down:

Health and medical content on this site is educational, not clinical advice. My calculators implement published clinical formulas (the Mifflin-St Jeor equation for BMR, the Cockcroft-Gault formula for GFR, etc.) and cite the peer-reviewed research behind them — but they're not a substitute for sitting across from a doctor who knows your history. Same goes for legal and tax content: I implement current IRS schedules and published statutory formulas, but your specific situation needs a professional.

Conflict of interest disclosure

nnng.com is independently operated — it's just me. The site earns revenue through display advertising and may include affiliate links in the future. But here's the thing I want to be clear about: those commercial relationships never touch the calculator formulas, the educational content, or which sources I cite. No financial institution, health product company, or advertiser has editorial input over anything on this site. Not now, not ever.

Fact-checking & corrections

I source formulas from the primary literature described above. Tax rates, legal thresholds, contribution limits, and financial benchmarks are reviewed for accuracy and updated when legislative or regulatory changes take effect. Every calculator page includes numbered source citations linking to the original reference material.

If you find an error — a broken formula, an outdated number, a misattributed source — please email hello@nnng.com. I'd rather fix something fast than pretend it was right. Errors get corrected promptly with a noted update date.

Published articles

Contact

For corrections, feedback, or editorial inquiries: hello@nnng.com