BMI & Healthy Weight Calculator
Interactive StudioCalculate Body Mass Index (BMI), WHO weight classification, BMI Prime, healthy target weight ranges, and Body Surface Area (BSA). Instant feedback with zero server storage.
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About BMI & Healthy Weight Calculator
Body Mass Index (BMI) is an anthropometric ratio used by the World Health Organization (WHO) to classify body weight relative to height: BMI = Weight (kg) / Height (m)².
WHO BMI Classifications for Adults: • Underweight: < 18.5 kg/m² • Normal Healthy Weight: 18.5 – 24.9 kg/m² • Overweight: 25.0 – 29.9 kg/m² • Obese Class I (Moderate): 30.0 – 34.9 kg/m² • Obese Class II (Severe): 35.0 – 39.9 kg/m² • Obese Class III (Very Severe): ≥ 40.0 kg/m²
How to use BMI & Healthy Weight Calculator
- Choose metric or imperial units.
- Enter your height and weight.
- Read your BMI value and its WHO category.
Worked examples
Input: 70 kg, 1.75 m
Result: BMI 22.9, in the normal range of 18.5 to 24.9.
Input: 95 kg, 1.75 m
Result: BMI 31.0, in the obese class I range.
Background
BMI = weight in kilograms / height in meters squared. The WHO categories for adults are underweight below 18.5, normal 18.5 to 24.9, overweight 25 to 29.9 and obese from 30.
BMI is a screening number, not a diagnosis. It cannot distinguish muscle from fat, ignores where fat is stored, and the cut-offs are not equally accurate across age, sex and ethnicity. It does not apply to children, who use age-specific percentile charts. Talk to a clinician about your own health.
Common mistakes
- Entering height in centimeters in a meters field, or the reverse.
- Reading a high BMI in a muscular athlete as unhealthy.
- Using adult categories for children or teenagers.
Frequently Asked Questions
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