Health calculators

Reference calculators for everyday body metrics. Convertitive runs everything locally — inputs never leave your device — and treats each tool as a screening reference, not a clinical diagnosis. Always pair the result with advice from someone who can see the rest of your medical picture.

BMI is the most-requested calculation on the internet and also the most-misunderstood: it’s a population-level screening metric, not a clinical body-composition measurement, and it systematically misclassifies muscular builds as overweight and small frames as healthy. The BMI tool here returns the value plus the WHO category band and the healthy weight range for your height, so you can see how close the boundary is rather than fixating on the label. The BMR and TDEE calculators use the Mifflin-St Jeor equation (the current best-validated formula) rather than the older Harris-Benedict which over-estimates by 5–10% for most adults. The body-fat calculator uses the US Navy tape method — three measurements with a flexible tape — which is the most accurate non-equipment estimate short of a DEXA scan. The pregnancy due-date tool implements Naegele’s rule (LMP + 280 days) and the conception-date variant, and shows gestational age plus trimester so you can sanity-check against a clinician’s estimate. None of this leaves your browser.