Accuracy and sources
Every formula and threshold is taken from a primary source: a clinical guideline, a peer-reviewed paper, a national standard or a recognised textbook. Sources are cited on the page, with links where possible. Where authorities disagree, we say so and explain which source we follow and why.
Expert review
Health content is reviewed by a medical doctor or another registered health professional in the relevant field. Engineering content is reviewed by a chartered or registered engineer. Finance and statistics content is reviewed by a qualified specialist. The reviewer and the review date are shown on every page.
Independence
We do not accept payment for coverage, and advertising (if any) never influences what we publish. Reviewers declare relevant conflicts of interest on their profiles.
Language
We write plainly and use neutral, person-first language about health and bodies. Calculators are tools for understanding, not diagnoses or professional sign-off.
Updates
Pages show when they were last updated and last reviewed. Substantive changes are noted on the page. See our corrections policy.