BMI Calculator Guide
What is the BMI Calculator?
BMI (Body Mass Index) is a widely used screening measure that estimates body fat based on your height and weight. While not a diagnostic tool, it provides a useful general guide to healthy weight ranges for adults.
How to calculate it manually
BMI = weight (kg) ÷ height² (m²). First convert height to metres (e.g. 175 cm = 1.75 m), then square it. Divide your weight in kilograms by that result.
Frequently Asked Questions
For adults 20+, 18.5 to 24.9 is considered healthy. Below 18.5 is underweight; 25–29.9 is overweight; 30 or above is classified as obese.
BMI cannot distinguish between muscle and fat mass. Athletes with high muscle mass may have a high BMI without excess body fat — it is best used as a general screening tool, not a clinical diagnosis.
The same scale applies to all adults aged 20+, though body fat percentages at the same BMI can differ between sexes and ethnicities.
For children and teenagers, BMI is interpreted differently — it is expressed as a percentile for age and sex rather than a fixed category.