Health calculators are screening tools, not diagnostic instruments. They take height, weight, age, sex, and a small number of measurable body dimensions, and return a categorised reading against a widely-accepted classification — WHO Technical Report Series 894 (2000) for adult BMI, CDC growth charts (2000) for pediatric weight-status percentiles, American Heart Association / American College of Cardiology 2017 for blood pressure staging, and validated formulas from peer-reviewed literature for BMR (Mifflin-St Jeor 1990), body fat percentage (US Navy method, Hodgdon & Beckett 1984), body surface area (Du Bois 1916, Mosteller 1987), and heart rate zones (Karvonen).

The categorisations these calculators produce are population-level generalisations. A BMI in the "overweight" band does not mean an individual person is unhealthy any more than a "normal" reading guarantees health — muscular athletes routinely score "overweight" on BMI while carrying low body fat, and older adults with normal BMI may have substantial visceral fat driving elevated cardiovascular risk. Every health tool on ScoutMyTool includes a limitations section explaining the population and conditions the formula was calibrated for, and where the calibration breaks down.

The health cluster is organised around body composition (BMI, ideal weight, body fat, lean body mass, BSA, waist-hip ratio), metabolic rate and nutrition (BMR, TDEE, calorie calculator, water intake), cardiovascular (blood pressure classification, heart rate zones), and life-stage tools (pediatric BMI, pregnancy due date, age calculators). Each category cites the authority whose classification it uses, and — where they differ — notes which populations (Asian populations under WHO Expert Consultation 2004 lower BMI thresholds, elderly populations under geriatric BMI research) have different clinically-recommended cutoffs.

Nothing in this cluster provides medical advice. These tools exist to let people track measurements over time, understand where their numbers fall against published clinical categories, and prepare informed questions for their clinicians. Consult a physician for any reading that concerns you, particularly if you are on medication, have a chronic condition, are pregnant, or are outside the age or population range the formula was validated for.

Reviewed by the ScoutMyTool editorial team. All health calculators cite WHO, CDC, AHA, NIH, or peer-reviewed medical literature as their underlying authority.