Enter a height between 50 and 250 cm (1 ft 8 in to 8 ft 2 in) and a weight between 10 and 400 kg (22 to 880 lb).
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BMI calculator
Enter your height and weight to see your body mass index, the WHO weight category it falls in and the healthy weight range for your height. It works in centimetres and kilograms or in feet, inches and pounds, and shows how far you are from the healthy range. Choose metric or imperial units and enter your height and weight. Your BMI, its category and the healthy weight range for your height update as you type. For adults aged 18 and over.
How it works
- Choose metric (cm, kg) or imperial (ft, in, lb) units.
- Enter your height and your weight.
- Read your BMI, its category and the healthy weight range for your height, and see where you are on the scale.
How BMI is calculated
BMI is your weight in kilograms divided by the square of your height in metres. For 70 kg at 1.75 m that is 70 ÷ (1.75 × 1.75) = 22.9. With feet, inches and pounds the calculator converts the units first, so the result is the same. BMI Prime is your BMI divided by 25, the upper limit of the healthy range: below 1.0 means you are under that limit.
The WHO categories
For adults, the World Health Organization uses these ranges: below 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight, and 30 or more obesity, split into class I (30 to 34.9), class II (35 to 39.9) and class III (40 or more). The table shows the weight that matches each range at your height.
Frequently asked questions
Is BMI accurate for everyone?
BMI is a quick screening measure, not a diagnosis. It does not tell muscle from fat, so very muscular people can have a high BMI without extra body fat, and older adults can have a normal BMI with little muscle. A waist measurement, body composition and a check by a doctor give a fuller picture.
Can I use it for children or teenagers?
No. For people under 18, BMI is compared with growth charts for their age and sex, as a percentile. This calculator uses the adult ranges, so ask a doctor or use a children's BMI chart for anyone younger.
Are my height and weight sent anywhere?
No. The calculation runs in your browser, and your last inputs are only kept in your browser's local storage, so they are there next time.
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