BMI Calculator

How to use the BMI calculator

Pick metric or imperial, enter your height and weight, and your BMI appears instantly with its WHO category and the healthy weight range for your height.

Reading the result

• Below 18.5: underweight - consider nutritional advice.
• 18.5 to 24.9: the normal range associated with the lowest health risk.
• 25 and above: overweight or obese - worth discussing lifestyle changes with a professional.

Method and sources

BMI is weight (kg) divided by height (m) squared, exactly as defined by the World Health Organization. The category boundaries shown - underweight below 18.5, normal 18.5-24.9, overweight 25 and above, obese 30 and above - come from WHO (WHO obesity and overweight fact sheet) and the US National Heart, Lung, and Blood Institute's healthy-weight range of 18.5-24.9 (nhlbi.nih.gov).

A note for Indian users

Research summarised by the WHO shows South Asian adults face higher risk of diabetes and heart disease at lower BMIs, and many Indian clinicians use 23 as the overweight cutoff. Use this tool as a guide, not a verdict.

Frequently asked questions