BMI Calculator
Calculate your Body Mass Index in metric or imperial units with ideal weight range.
BMI is a screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, body composition, or age. Consult a qualified healthcare professional for personalised health advice.
What is BMI Calculator?
BMI Calculator computes your Body Mass Index from your height and weight in either metric (cm, kg) or imperial (ft/in, lb) units. The result is displayed on a colour-coded scale — Underweight, Normal weight, Overweight, and Obese — along with the healthy weight range for your specific height.
The calculator uses the standard WHO BMI formula: BMI = weight(kg) ÷ height(m)². All inputs are reactive sliders with instant feedback.
BMI is a screening tool used by health organisations worldwide as a quick population-level indicator. It is not a diagnostic measure and does not account for muscle mass, body fat percentage, or individual health conditions.
Common Use Cases
- Quick personal health screening
- Tracking BMI changes over time with diet and exercise
- Understanding healthy weight range for a given height
- Converting weight goals into BMI context
- Educational reference for understanding BMI categories
How to Use BMI Calculator
- Choose Metric (cm, kg) or Imperial (ft/in, lb).
- Set your height and weight using the sliders.
- Your BMI and category appear instantly.
- Check the healthy weight range table to see how your BMI compares to WHO categories.
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FAQ
What is BMI and what does it measure?
BMI (Body Mass Index) is a numerical value calculated from height and weight using the formula: BMI = weight(kg) ÷ height(m)². It is used as a simple screening tool to categorise individuals into weight ranges (Underweight, Normal, Overweight, Obese) that may correlate with health risks. It does not directly measure body fat.
What is a normal BMI?
According to the World Health Organization (WHO), a BMI of 18.5 to 24.9 is considered normal weight for adults. Below 18.5 is Underweight, 25–29.9 is Overweight, and 30 or above is Obese. Different organisations may use slightly different cutoffs for specific populations.
Is BMI accurate for athletes and muscular people?
No. BMI does not distinguish between muscle mass and fat mass. A highly muscular person may have a high BMI but very low body fat, while an elderly person may have a normal BMI but high body fat percentage. For athletes and bodybuilders, body fat percentage measurements are more informative.
Is BMI different for children?
Yes. BMI for children and teenagers (under 20) is interpreted differently using age- and sex-specific percentile charts, not the fixed adult cutoffs. This calculator is designed for adults. Consult a paediatrician for BMI assessment in children.
What should I do if my BMI is outside the normal range?
BMI is a screening indicator, not a diagnosis. If your BMI is outside the 18.5–24.9 range, consult a qualified doctor or registered dietitian for a personalised assessment. Do not make significant dietary or medical decisions based solely on BMI.