The formulas, named and cited
Energy estimates use the Mifflin-St Jeor equation (Mifflin et al., 1990) as the default, with the revised Harris-Benedict (Roza & Shizgal, 1984) and Katch-McArdle shown alongside for comparison. Body fat estimation uses the U.S. Navy circumference method (Hodgdon & Beckett, 1984). Activity energy is split into NEAT (Levine, 2002) and exercise minutes anchored to the WHO 2020 physical-activity guidelines. Weight-change projections simulate week by week, recomputing energy expenditure as body weight falls (Leibel et al., 1995; Hall et al., 2011) instead of assuming the static “3,500 kcal per pound forever” shortcut — whose origin (Wishnofsky, 1958) and limits we cite rather than hide. Protein guidance follows the resistance-training and weight-loss literature (Morton et al., 2018; Helms et al., 2014; Mettler et al., 2010). The full citation for every claim appears in the Sources section of the page that makes it.
What runs where
All calculation happens client-side in your browser — your inputs are never transmitted, stored, or seen by us. The site is plain static HTML, CSS and JavaScript; there are no accounts and no databases. Exports (Markdown, PDF) are generated locally on your device.
What we claim — and what we don't
Formula-based estimates carry roughly ±10% uncertainty for most people, and we say so on the pages themselves. We enforce minimum-intake floors (1,200 kcal/day for women, 1,500 for men) in every calculation and will cap or warn rather than print numbers below them. Nothing on this site is medical advice: calculators inform decisions; they don't make them. Pages touching medically supervised weight loss say explicitly that dose and treatment questions belong to your prescriber.
Who builds this
CaloriesKit is built and maintained by Murugan Vellaichamy, a software engineer — not a clinician, which is exactly why every health-relevant number is sourced to published research rather than to our opinion. The honest division of labour: we do the math and the engineering; the science comes from the cited literature; medical judgement stays with professionals.
Corrections
Found an error in a formula, a citation, or a claim? Tell us — corrections with a citation are handled with priority, and we'd rather fix a page than defend it.