Editorial Policy

Every calculator and article is drafted by a Calcxo writer with subject-matter experience in finance, math, or health. We start from primary sources — published formulas, official guidance, or peer-reviewed references — never by paraphrasing other calculator websites.

Drafts include the formula in plain notation, a worked example, edge cases, and the assumptions a reader should know before using the result. Anything we cannot verify, we leave out.

Each formula is implemented in code and tested against at least three independent reference values: a published worked example, a manual calculation, and (where applicable) the output of an established tool such as a financial calculator or scientific spreadsheet.

We document the exact formula on the page so readers can audit the math themselves. If a formula has commonly confused variants (for example APR vs. APY, or BMI vs. BMI prime), we explain the difference rather than picking one silently.

We prefer primary sources: regulators, standards bodies, government statistics agencies, peer-reviewed journals, and official product documentation. Secondary sources are used only when they summarize a primary source faithfully, and we link the primary source whenever possible. See our Sources & Methodology page for the full list.

Before publishing, every page is reviewed by a second editor for accuracy, clarity, and accessibility. Calculators receive an additional engineering review that re-runs the test cases on the production build. Our full review cadence is described in the Review Policy.

Pages display a visible Last updated date. Substantive updates — a corrected formula, a new edge case, a refreshed data source — bump that date and are summarized in the page's changelog when the change affects results. Cosmetic edits do not change the date.

If you spot an error, email corrections@calcxo.com with the page URL and a short description. Verified corrections are published within 7 days, and material corrections are noted at the bottom of the page so the change is transparent.

Calcxo is independently funded. We do not accept payment to feature, rank, or omit calculators, and our editorial decisions are not influenced by advertisers or partners. If a page ever contains a sponsored element, it will be clearly labeled.