BMI Calculator — Body Mass Index
Calculate your Body Mass Index instantly in metric or imperial units. BMI is the universal first-check doctors use to flag underweight, healthy, overweight and obese ranges, calculated from just your height and weight. Enter your measurements in kilograms and centimetres — or pounds, feet and inches — and this calculator returns your BMI, your WHO category, the healthy weight range for your height, and a visual gauge showing exactly where you stand. It works for adults of any age, explains every number it shows, and computes everything locally in your browser.
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How to calculate your BMI online for free
- 1
Choose your preferred units: metric (kg + cm) or imperial (lb + ft/in).
- 2
Enter your height and weight.
- 3
Your BMI, category and healthy weight range update instantly.
- 4
Read the gauge and guidance to understand what your number means.
Why use this bmi calculator tool?
Metric & imperial units
Switch between kg/cm and lb/ft-in with instant conversion — no separate calculations needed.
WHO category & gauge
A clear visual scale shows whether you're underweight, normal, overweight or obese, and exactly where your BMI falls.
Healthy weight range
See the weight window (BMI 18.5–24.9) for your height, so you know your target range — not just a single number.
Instant, private results
Everything recalculates as you type, and nothing is stored or transmitted — your data stays yours.