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BMI Calculator

Calculate Body Mass Index with WHO health category — underweight, normal, overweight, or obese.

About This Calculator

BMI (Body Mass Index) is calculated as weight in kg divided by height in metres squared. The WHO uses BMI as a primary screening tool for weight categories associated with health risks. This calculator supports both metric and imperial units.

How to Use This Calculator

  1. 1Select your preferred unit system
  2. 2Enter your height accurately
  3. 3Enter your current body weight
  4. 4Click Calculate BMI to see results with health category and ideal weight range

Formula Used

BMI = Weight (kg) / Height (m)² | Imperial: BMI = (Weight lbs / Height inches²) × 703

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FAQ

Frequently Asked Questions

Common questions about the bmi calculator answered.

What is a healthy BMI?+
A BMI between 18.5 and 24.9 is considered the healthy normal weight range for adults by the World Health Organization. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is classified as obese.
Is BMI accurate for athletes?+
BMI is less accurate for athletes with high muscle mass, as muscle is denser than fat. A muscular person may show a high BMI despite having low body fat. For athletes, body fat percentage measurements are more informative.
What is my ideal weight for my height?+
The ideal weight range for a BMI of 18.5 to 24.9 is shown in the results after calculation. This represents the weight range associated with the lowest health risk for your specific height.
Does BMI differ for Asian populations?+
Yes. Research suggests people of Asian descent may face health risks at lower BMI values. The WHO recommends additional cutoff points of 23 (increased risk) and 27.5 (high risk) for Asian populations, including South Asians.
How can I improve my BMI?+
For overweight BMI, combine regular aerobic exercise (150+ minutes per week), strength training, a calorie-controlled whole-food diet, adequate sleep, and stress management. Always consult a doctor before making major lifestyle changes.

BMI Categories by WHO

The WHO classifies BMI into four main categories for adults: Underweight (below 18.5) carries risks of malnutrition and bone loss. Normal weight (18.5 to 24.9) represents the lowest health risk. Overweight (25 to 29.9) carries moderately increased risk of diabetes and heart disease. Obese (30 and above) carries significantly higher risk of multiple chronic conditions.

  • Underweight: BMI below 18.5
  • Normal Weight: BMI 18.5 to 24.9
  • Overweight: BMI 25 to 29.9
  • Obese Class 1: BMI 30 to 34.9
  • Obese Class 2: BMI 35 to 39.9

BMI for Different Populations

BMI thresholds developed primarily from studies on European populations. For South Asian, East Asian, and Southeast Asian populations, health risks begin at lower BMI values. Indian health guidelines recommend considering overweight classification starting at BMI 23 and obesity at 27.5, rather than the global thresholds of 25 and 30.

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