BMI Calculator
Enter your height and weight to get your Body Mass Index and the WHO category it falls into, in metric or imperial units, along with the weight range that would put you in the healthy band for your height. BMI is weight divided by height squared, which makes it a measure of mass relative to size and nothing more: it was designed to describe populations, and it says nothing about what that mass is made of or where it sits on the body. That is why it works reasonably well as a first screening question across a large group and poorly as a verdict on any individual. Read it as one number among several rather than a diagnosis. Your inputs stay on your device and are never sent anywhere.
Healthy range: 53.5–72.0 kg
How to use
- Pick metric or imperial units.
- Enter your height and weight.
- Read your BMI value and category.
- Compare your weight to the healthy range for your height.
Frequently asked questions
- How is BMI calculated?
- BMI = weight (kg) ÷ height (m)². Imperial inputs are converted to metric for the formula.
- What are the categories?
- Per WHO: under 18.5 is underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese.
- Is BMI a good measure of health?
- BMI is a quick screening tool, but it doesn't distinguish muscle from fat and isn't ideal for children, athletes, or pregnant people. Talk to a doctor for a real assessment.
- Are my values stored?
- Only in your browser's local storage so the form remembers them next time — nothing is uploaded.
- Why is BMI misleading for muscular people?
- Because it measures mass, not composition. Muscle is denser than fat, so a well-trained athlete can carry enough of it to land in the overweight or obese range while having very little body fat. The formula has no way to tell the two apart - it only ever sees total weight against height.
- Does BMI apply to children?
- Not in the same way. A child's healthy ratio of weight to height changes continuously with age and differs between boys and girls, so the fixed adult thresholds do not transfer. Paediatric assessment uses BMI-for-age percentile charts instead, comparing a child against others of the same age and sex.
- Are the thresholds the same for everyone?
- Not universally. The standard cut-offs were derived largely from European populations, and several health authorities use lower thresholds for people of Asian descent, where the risks associated with a given BMI tend to appear at a lower value. Waist measurement is often a more useful companion figure than BMI alone.
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