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BMI Calculator (Body Mass Index)

Calculate your Body Mass Index and see which WHO category it falls into, plus the healthy weight range for your height.

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What is it?

BMI is a simple ratio of weight to height used worldwide to screen weight categories in adults.

It's quick and useful at population level, but it doesn't measure body fat directly.

How it's calculated

BMI = weight (kg) ÷ height (m)².

Categories follow the World Health Organization: under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30+ obesity.

The healthy weight range is the weight that gives a BMI of 18.5–24.9 at your height.

BMI = kg / m²

How we calculate · Last reviewed: September 1, 2026

How to interpret your result

Use BMI as one data point together with waist circumference, fitness and how you feel.

Muscular people often have a high BMI with low body fat.

Estimates for healthy adults. Not medical advice — talk to a qualified professional about your specific situation.

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Frequently asked questions

Is BMI accurate?

It's a screening tool, not a diagnosis. It doesn't distinguish muscle from fat, and cut-offs can differ for some ethnic groups.

Is BMI valid for children?

No. Children and teens use age- and sex-specific percentiles. This calculator is for adults.

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