Body & WeightQuetelet Index (BMI = kg/m²)

BMI Calculator

The Body Mass Index (BMI) calculator estimates whether you are underweight, normal weight, overweight, or obese based on your height and weight according to WHO guidelines.

Body & Weight

BMI Calculator

Calculate your Body Mass Index (BMI) and determine your healthy weight category.

Height50 – 250 cm
cm
Weight20 – 350 kg
kg
WHO Adult BMI SpectrumNormal / Healthy
1242+
24.5kg/m²
Normal / Healthy
Underweight
12-18.5
Normal / Healthy
18.5-24.9
Overweight
25-29.9
Class I Obesity
30-34.9
Class II/III Obesity
35-45
WHO Healthy Weight56.7 – 76.3 kg
BMI Prime Ratio0.98

Evidence-based estimations. Consult a physician for personalized guidance.

Clinical Formula & Calculation Standard

Official clinical definitions and validated mathematical models

Body Mass Index (BMI), BMI Prime & Ponderal Index

BMI = Weight (kg) / [Height (m)]² | US: 703 × Weight (lb) / [Height (in)]²

Body Mass Index is an epidemiological screening tool developed by Adolphe Quetelet. BMI Prime normalizes the value against the upper normal threshold (BMI / 25), while the Ponderal Index (kg/m³) provides greater volumetric accuracy across tall and short statures.

WHO Adult BMI Classification (Age 20+)

ClassificationBMI (kg/m²)BMI PrimeRisk of Comorbidities
Severe Thinness< 16.0< 0.64Very High (Malnutrition, Osteoporosis)
Moderate Thinness16.0 – 16.90.64 – 0.68High
Mild Thinness17.0 – 18.40.68 – 0.74Moderate
Normal Weight18.5 – 24.90.74 – 1.00Low / Baseline
Overweight (Pre-obese)25.0 – 29.91.00 – 1.20Increased
Obese Class I30.0 – 34.91.20 – 1.40High (Cardiovascular, Diabetes)
Obese Class II35.0 – 39.91.40 – 1.60Very High
Obese Class III≥ 40.0≥ 1.60Extremely High (Severe Clinical Risk)

Source: World Health Organization (WHO) Technical Report Series.

Clinical Insights & Practical Usage

  • Healthy weight range corresponds to weights yielding a BMI between 18.5 and 24.9 kg/m² for the measured height.
  • Children and teens (ages 2–20) are evaluated via CDC age-and-sex specific BMI percentiles (Underweight: <5th percentile, Healthy: 5th–85th, Overweight: 85th–95th, Obese: ≥95th).
  • BMI does not directly differentiate between muscle mass, bone density, and adipose tissue. Muscular individuals may be classified as overweight despite low adiposity.

Medical Disclaimer: BMI is an epidemiological screening metric and not a diagnostic measure of body composition or personal cardiometabolic risk.

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