BMI Calculator
Calculate Body Mass Index from height and weight
About BMI Calculator
BMI (Body Mass Index) is a simple health screening measurement calculated from height and weight. It provides a quick indicator of whether a person's weight is in a healthy range. This free BMI Calculator supports both metric and imperial units, instantly shows your BMI score and health category (Underweight, Normal, Overweight or Obese), and displays your position on the standard BMI scale.
How to Use BMI Calculator
- 1Select your unit system: Metric (kg/cm) or Imperial (lbs/inches).
- 2Enter your height and weight in the fields provided.
- 3Your BMI score and health category appear instantly.
- 4See the BMI scale to understand where your score falls.
Common Use Cases
BMI is a screening tool, not a diagnosis. It doesn't measure body fat directly — athletes may have high BMI due to muscle mass. Consult a doctor for health decisions.
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Frequently Asked Questions
How is BMI calculated?
BMI = Weight (kg) / Height² (m²). In metric: if you weigh 70kg and are 1.75m tall, BMI = 70 / (1.75²) = 70 / 3.0625 = 22.9. In imperial: BMI = (Weight in lbs × 703) / Height² in inches.
What are the BMI categories?
WHO BMI categories: Underweight = below 18.5, Normal weight = 18.5–24.9, Overweight = 25.0–29.9, Obese Class I = 30.0–34.9, Obese Class II = 35.0–39.9, Obese Class III = 40.0 and above. Note: Asian populations including Indians have lower BMI thresholds — "overweight" is often set at 23 and "obese" at 27.5.
Is BMI accurate for everyone?
BMI is a population screening tool with known limitations. It can overestimate risk for muscular people (athletes have high BMI from muscle, not fat) and underestimate risk for people with high body fat but low muscle (sarcopenic obesity). For children, BMI is interpreted differently using age/gender-specific charts.
What is a healthy BMI for Indians?
For South Asian populations including Indians, researchers recommend lower BMI thresholds: Underweight < 18.5, Normal = 18.5–22.9, Overweight = 23.0–24.9, Obese ≥ 25.0. This is because Indians tend to carry more body fat at lower BMI values compared to Western populations.