How we work
Methodology & data sources
Every Kalcify calculator is built against primary sources — the same publications, statutes and classifications that the underlying authority publishes itself. This page explains where the numbers come from, how often they are reviewed, and how to flag a mistake.
Computation
How calculations are produced
Calculator arithmetic runs in your browser. Network lookup tools work differently: they send requests to retrieve information. Local calculation does not mean that the whole page is offline; hosting, analytics, advertising and consent services have separate data flows.
Calculator logic is implemented from the textual rules of the originating authority (for example, the IRS publication that defines a tax bracket, the WHO classification that defines a BMI band, or the W3C specification that defines color-contrast). The cited source and tax year describe the inputs used. The page date alone does not establish that those inputs are current.
Site services
Measurement and privacy
On ordinary visits to the main site, Kalcify loads Google Analytics 4 for usage measurement, Google AdSense for advertising, and Google Funding Choices for consent choices. Embedded tools and excluded QA sessions do not load these services. Loading an advertising script does not guarantee that an ad appears.
Privacy policy and regional consent defaultsAuthorities
8Primary sources by category
Finance & tax (United States)
Internal Revenue Service (IRS)Federal income tax brackets, standard deduction amounts, payroll tax rates, retirement contribution limits.
Finance & tax (United Kingdom)
HM Revenue & Customs (HMRC)Income Tax bands, National Insurance categories and thresholds, VAT rates, capital gains and dividend rules.
Finance & tax (Canada)
Canada Revenue Agency (CRA)Federal and provincial tax brackets, TFSA and RRSP limits, EI / CPP contribution rates.
Finance & tax (Australia)
Australian Taxation Office (ATO)Resident tax rates, Medicare levy, HECS-HELP repayment thresholds, stamp-duty schedules per state.
Finance & tax (Germany)
Bundesministerium der FinanzenLohn- und Einkommensteuer, Solidaritätszuschlag, Kirchensteuer, Sozialversicherung.
Health & wellness
World Health Organization (WHO)BMI classification bands, daily reference intake values, alcohol unit definitions.
Blood alcohol & impairment
National Highway Traffic Safety Administration (NHTSA)US BAC limits per state, Widmark formula reference, elimination-rate ranges.
Web standards (developer tools)
W3C, WHATWG, IETFColor-contrast ratios (WCAG 2.2), JSON specification (RFC 8259), HTML/CSS specifications.
Review
Update cadence
“Last updated” records a change to the page’s published text, including information drawn from shared sources. Layout changes that leave the text unchanged do not reset the date. It is not a date of legal review or a guarantee that a formula or source has been rechecked.
Publication dates are retained when a page is updated. Republishing unchanged content does not refresh either date. Calculator inputs and automatically displayed dates do not count as editorial updates. Tool titles and descriptions count; recommendations and catalog listings do not.
Check a tool’s stated year, assumptions and sources before relying on its result. Use the contact details below to flag outdated information.
Corrections
Spot a mistake?
If a calculator returns a number you cannot reconcile with the official source, please write to contact@kalcify.org with the tool URL, the inputs you used, the result you got and the source you are comparing against. Corrections are prioritised over feature work and the response commitment on the Contact page applies.
Limits
What Kalcify is not
Kalcify is informational. Tax calculators produce estimates, not filings. Health calculators are screening aids, not medical diagnoses. For decisions with material financial or medical consequences, consult a qualified professional in your jurisdiction. The full disclaimer lives in the Terms of Service.