Body Mass Index (BMI) Calculator

Calculate your BMI and see the adult category & common caveats. Private by design—everything runs locally in your browser.

Inputs

For adults (20+). Ages 2–19 require growth-chart interpretation with a professional.

Result

Your BMI
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Category
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Health Risk
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Formula

Metric: BMI = weight(kg) / [height(m)]²
Imperial: BMI = weight(lbs) / [height(in)]² × 703

Examples

Adult BMI categories

CategoryBMI
Underweight< 18.5
Normal (Healthy weight)18.5–24.9
Overweight25.0–29.9
Obese≥ 30

What is BMI and how is it calculated?

Body Mass Index (BMI) is a simple ratio of weight to height. In metric units: BMI = weight(kg) / [height(m)]². In imperial units: BMI = weight(lbs) / [height(in)]² × 703. This tool supports both systems and calculates instantly in your browser.

Adult BMI categories

  • Underweight: < 18.5
  • Normal (Healthy weight): 18.5–24.9
  • Overweight: 25.0–29.9
  • Obese: ≥ 30

Important caveats

  • Not body fat: BMI doesn’t distinguish fat from muscle.
  • Athletes & muscular builds: Can read “high” without excess fat.
  • Age, sex, ethnicity: Health risks at a given BMI can differ.
  • Children/teens (2–19): Use growth-chart–based interpretation with a professional.

Disclaimer: This BMI calculator is for general information and adult screening only and is not medical advice.

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