BMI & Body Composition
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Reference Tables
BMI Categories and Associated Health Risk
World Health Organization standard BMI classifications for adults aged 20 and older.
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 16.0 | Severe underweight | Very high risk of nutritional deficiency, organ failure, and immune dysfunction |
| 16.0 – 16.9 | Moderate underweight | High risk of nutritional deficiency and associated complications |
| 17.0 – 18.4 | Mild underweight | Moderate risk — monitoring and nutritional assessment recommended |
| 18.5 – 24.9 | Normal healthy weight | Lowest health risk — associated with best long-term outcomes |
| 25.0 – 29.9 | Overweight | Mildly increased risk of cardiovascular disease, Type 2 diabetes, and hypertension |
| 30.0 – 34.9 | Obese Class I | Moderate risk — medical evaluation recommended |
| 35.0 – 39.9 | Obese Class II | High risk — medical supervision strongly recommended |
| 40.0 and above | Obese Class III | Very high risk — immediate medical evaluation recommended |
BMI ranges for adults over 65 may differ. Research suggests a BMI of 25 to 27 may be associated with better health outcomes in older adults. Consult your healthcare provider for age-appropriate interpretation.
Important Health Disclaimers
This calculator is provided for general informational and educational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of your physician or other qualified health provider with any questions you may have regarding your weight, body composition, nutrition, or overall health.
BMI is a population-level screening tool and has significant limitations when applied to individuals. It does not distinguish between muscle mass and fat mass, does not account for fat distribution, and may misclassify muscular athletes as overweight or obese. BMI may also be less accurate for older adults, pregnant women, children under 20, and individuals of certain ethnic backgrounds where body composition norms differ from the populations used to establish standard ranges.
Body fat percentage results produced by this calculator are estimates based on the Deurenberg population formula and should not be treated as precise individual measurements. Clinical body composition assessment methods such as DEXA scan, hydrostatic weighing, or air displacement plethysmography are required for precise measurement.
Calorie estimates produced by this calculator are based on validated population formulas and represent statistical averages. Individual metabolic rates vary based on genetics, hormonal status, medication use, and other factors. These estimates should be used as a general starting point only and not as a precise prescription for caloric intake.
If you are under the age of 20, pregnant, postpartum, managing a chronic health condition, or have a history of disordered eating, please consult a qualified healthcare provider before using BMI or body composition metrics as health guides.
This tool does not store personally identifiable health information on any external server. All data is stored locally in your browser using localStorage and remains entirely on your device.