BMI calculator
Enter your height and weight to get your body mass index, the WHO category for adults and the weight range that matches your height.
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Runs in your browser. Nothing is uploaded.
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Your measurements
Your BMI
— kg/m²
WHO category for adults
Enter your height and weight to see your BMI.
| BMI (kg/m²) | Category |
|---|---|
| Below 18.5 | Underweight · your result |
| 18.5 to 24.9 | Normal weight · your result |
| 25 to 29.9 | Pre-obesity (overweight) · your result |
| 30 to 34.9 | Obesity class I · your result |
| 35 to 39.9 | Obesity class II · your result |
| 40 or more | Obesity class III · your result |
Under 18, BMI is compared with children of the same age and sex on growth charts, and the result is a percentile. The adult categories don’t apply, so none is shown here. WHO publishes these charts for ages 5 to 19, and many countries use their own.
- Normal weight range for your height
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How it’s calculated
BMI = weight (kg) ÷ height (m)²
Categories: World Health Organization (WHO), for adults aged 18 and over.
What BMI doesn’t tell you
- Muscle. Athletes and very muscular people can have a high BMI without excess body fat.
- Older adults. With age, muscle is often replaced by fat, which a normal BMI can hide.
- Pregnancy. BMI categories don’t apply during pregnancy.
- Children and teenagers. Their BMI is read on growth charts by age and sex, not with the adult categories.
- Origin and body shape. At the same BMI, health risks differ between populations, and BMI doesn’t show where fat is stored. Some countries use lower cut-off points for people of Asian descent.
BMI is a screening figure, not a diagnosis. This result is general information, not medical advice.
How it works
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Choose your units
Kilograms and centimetres, or pounds, feet and inches. Switching converts what you have already typed.
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Enter your height and weight
The result updates as you type. Say whether the BMI is for an adult or for someone under 18.
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Read the result in context
See where the BMI sits on the WHO scale, the weight range that matches the height, and what BMI can’t tell you.
Frequently asked questions
How is BMI calculated?
Body mass index is your weight in kilograms divided by the square of your height in metres. For 70 kg and 1.75 m: 70 ÷ 1.75² = 22.9. In pounds and inches, the same result comes from 703 × weight (lb) ÷ height (in)².
What are the WHO BMI categories for adults?
The World Health Organization classifies the BMI of adults as follows: below 18.5, underweight; 18.5 to 24.9, normal weight; 25.0 to 29.9, pre-obesity, often called overweight; 30.0 to 34.9, obesity class I; 35.0 to 39.9, obesity class II; 40 or more, obesity class III. Source: WHO, “A healthy lifestyle – WHO recommendations” and the fact sheet “Obesity and overweight”.
Why is no category shown for children and teenagers?
A child’s body changes as they grow, so the same BMI doesn’t mean the same thing at 8 and at 16, or for girls and boys. Under 18, BMI is compared with children of the same age and sex on growth charts, and the result is a percentile. WHO publishes growth references for ages 5 to 19, and many countries use their own charts. The calculator gives the BMI, but no adult category that wouldn’t apply.
What doesn’t BMI tell you?
BMI doesn’t measure body fat or show where it is stored. It can be high in muscular people, it can look normal in older adults who have lost muscle, and its categories don’t apply during pregnancy. At the same BMI, risks also differ between populations, which is why some countries use lower cut-off points for people of Asian descent. It is a screening figure, not a diagnosis.
What is a normal weight for my height?
For adults, the WHO normal range is a BMI of 18.5 to 24.9. The calculator turns it into weights for your height: weight = BMI × height (m)². At 1.75 m, that is about 56.7 to 76.3 kg.
Is my height or weight stored?
No. The calculation runs in your browser and your measurements are never sent anywhere. Only your choice of units is remembered on this device.