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BMI Calculator

See your Body Mass Index and which WHO category you fall into

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Your data

Weight

Height

Sex — used only for the reference ideal weight

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Your panel

0.0 kg/m²

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1618.5253040

Healthy weight range for your height (BMI 18.5–24.9)—

Difference from the healthy range—

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How it's calculated

Weight divided by height squared

The BMI calculator divides weight by height squared to indicate whether your weight is adequate, according to the World Health Organization categories. For example, 75 kg and 1.75 m give a BMI of 24.5 — within the normal weight range (18.5 to 24.9).

The Body Mass Index is a simple screening tool created by Adolphe Quetelet and adopted by the WHO. It does not measure body fat directly, but relates your weight to your height to flag whether there is excess or lack of weight.

BMI = weight (kg) ÷ height (m)²

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Height converted from cm to meters
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Height squared (height × height)
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Weight divided by height squared
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Healthy weight range: 18.5 × height² to 24.9 × height²
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Understand the terms

BMI: Body Mass Index — the ratio between weight and height squared, in kg/m².
WHO categories: Underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), obesity I (30–34.9), II (35–39.9) and III (≥40).
Limitation: BMI does not distinguish fat from muscle. Muscular athletes can have a high BMI without excess fat.

See the full glossary →

Disclaimer: estimation tool for informational and planning purposes, using WHO reference categories (2024) for adults aged 20 to 59. BMI does not replace a clinical assessment and does not measure body composition. Children, pregnant women, older adults and athletes require specific analysis. It does not replace guidance from a doctor or dietitian.

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Frequently asked questions — BMI

What is BMI and what is it for?

Body Mass Index relates your weight to your height squared. It is a quick screening tool to indicate whether your weight is adequate, but it does not directly measure fat or muscle mass.

What is the BMI formula?

BMI = weight (kg) ÷ height (m)². Example: 80 kg and 1.75 m → 80 ÷ (1.75 × 1.75) = 26.1.

What are the WHO BMI categories?

Below 18.5: underweight; 18.5 to 24.9: normal; 25 to 29.9: overweight; 30 to 34.9: obesity class I; 35 to 39.9: class II; 40 or more: class III.

Does BMI work for athletes and people who lift weights?

Not accurately. People with a lot of muscle mass can have a high BMI without excess fat. Use body fat percentage or FFMI for a fairer reading.

Is BMI different for men and women?

The WHO formula and categories are the same for both sexes in adults. Body composition differs, so interpret BMI alongside other measurements.

What is the ideal weight for my height?

The healthy range corresponds to a BMI between 18.5 and 24.9. The calculator converts those ranges into kilograms for your height.

Do children and older adults use the same BMI?

No. Children and teenagers use age- and sex-specific curves (percentiles); for older adults the cut-offs may change. This calculator is for adults aged 20 to 59.

📚 Learn more — official sources

🏛️ Organization WHO — BMI categories World Health Organization: official definition and classification of Body Mass Index by category. See official source → 🏛️ Organization CDC — Adult BMI U.S. Centers for Disease Control and Prevention: how BMI is calculated and interpreted for adults. See official source → 📘 Guide NIH / NHLBI — BMI calculator National Heart, Lung, and Blood Institute reference on BMI calculation and weight categories. See official source → 🔬 Reference Harvard Health — How useful is BMI? Harvard Medical School: the use of BMI and its limitations in assessing health. See official source →

BMI

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