How every calculator works

Source hierarchy. Peer-reviewed research first (PubMed PMID or DOI linked inline), meta-analyses where the literature is large enough to warrant one, then named-author textbooks (Helms, Schoenfeld, Daniels, ACSM editions). Field experiments and cohort studies are cited with sample size and population. Vendor blogs, listicles, and unattributed "studies show" claims are not acceptable sources. Citation rules are enforced — see editorial standards.

Determinism. Every calculator runs in the browser and computes its output from the inputs you provide. No server-side estimation, no profile matching, no personalisation — same inputs, same numbers, every time. This is a reference hub, not a coaching app.

Named limits. Every formula's domain of applicability is documented on its methodology page. Mifflin-St Jeor was derived on American adults aged 19–78 and is most accurate there; Katch-McArdle is preferred when body-fat percent is measured (DEXA / hydrostatic), not eyeballed; Riegel's race predictor loses accuracy outside the 5K–marathon band; FFMI's 25 ceiling is an observational claim from Kouri 1995 (n=157), not a biological law. Tools say so before they show the number.

High-risk tools. Direct 1RM testing, VO2-max field tests, and elite-percentile strength standards carry an elevated-caution banner per editorial standards. These are estimators, not training prescriptions; consult a coach or physician before changing load.

Update cadence. Each formula and its coefficients are dated at first publication. New research is integrated quarterly with version notes in the page changelog — coefficients are not silently rotated. Material methodology changes are flagged at the top of the affected page until the next quarterly review.

Corrections. Append-only at /corrections/. When a methodology page, tool output, or article is fixed, a dated entry is added to the corrections log. Nothing is silently rewritten.