A free, accurate, and beautifully simple tool to help you understand your Body Mass Index — based on WHO guidelines.
BMI Calculator computes your Body Mass Index instantly from your height and weight — in both metric and imperial units. Beyond the number, we show you where you sit on the BMI scale, your healthy weight range, your BMI Prime, and a full classification table.
The result is a clear, complete picture of your BMI in seconds — no sign-up, no apps, no cost.
All calculations follow the WHO (World Health Organization) standard BMI formula and classification thresholds. We use the metric formula BMI = kg/m² as the primary calculation, with imperial inputs converted accurately before computing.
We also display BMI Prime (the ratio of your BMI to the upper limit of the normal range) and Ponderal Index as supplementary metrics for a fuller picture of body composition.
BMI is a screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, fat distribution, age, sex, or ethnicity. A single BMI number should never be used alone to make health decisions. We encourage all users to consult a qualified healthcare professional for personalised guidance.
All calculations happen entirely in your browser. Your height and weight are never sent to or stored on our servers. We take your privacy seriously — see our Privacy Policy for full details.