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BMI Calculator

The BMI calculator estimates body fat based on height and weight. While useful as a screening tool, it should be interpreted alongside other clinical assessments of body composition and health.

Clinically reviewed

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Enter values to see your result.

How to Use the Calculator

  1. Enter weight in kilograms.
  2. Enter height in centimeters.
  3. View your BMI result instantly.

What the BMI Result Means

BMI categories help classify weight status: Underweight (<18.5), Normal weight (18.5-24.9), Overweight (25-29.9), Obesity Class I (30-34.9), Class II (35-39.9), and Class III/Severe (≥40). These classifications guide clinical discussions about weight management and health risks.

When to Use This Calculator

  • Initial screening for obesity and underweight
  • Eligibility assessment for bariatric surgery
  • Risk stratification for metabolic syndrome
  • Monitoring weight management interventions

Frequently Asked Questions

What are the BMI categories?

WHO classifications: Underweight (<18.5), Normal (18.5-24.9), Overweight (25-29.9), Obesity Class I (30-34.9), Class II (35-39.9), and Class III/Severe (≥40).

Why might BMI be misleading?

BMI does not distinguish between muscle and fat mass. Athletes may have high BMI but low body fat. Conversely, elderly individuals may have normal BMI but high visceral fat. Waist circumference and body composition assessments provide additional insight.

References & Guidelines