BMI calculator
Enter your height and weight to see your body mass index, the adult category it falls in, and the healthy-weight range for your height.
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How BMI is calculated
Body mass index compares your weight with your height. In metric units it is your weight in kilograms divided by your height in meters squared. In US units it is your weight in pounds divided by your height in inches squared, multiplied by 703.
For example, someone who is 5 ft 9 in (69 inches) and weighs 160 lb has a BMI of 160 ÷ 69² × 703 = 23.6.
Adult BMI categories
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Healthy weight |
| 25 to 29.9 | Overweight |
| 30 and above | Obesity |
What BMI can and can't tell you
BMI is a quick screening number, not a diagnosis. It doesn't measure body fat directly, so muscular people can score high, and it can miss extra fat in people with little muscle. Where you carry weight also matters: waist size is a useful second check.
These categories are for adults aged 20 and over. Children and teens use BMI-for-age percentiles instead, which compare them with others of the same age and sex.
This calculator gives general information, not medical advice. Talk to a doctor about your weight and health.
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Questions people ask
What is a healthy BMI?
For adults, a BMI from 18.5 to 24.9 is classed as a healthy weight.
Is BMI accurate for athletes?
Not always. Muscle weighs more than fat, so very muscular people can have a high BMI without carrying extra fat.
Can I use this calculator for a child?
No. Children and teens are assessed with BMI-for-age percentiles, which depend on age and sex. Ask a pediatrician or use a child BMI calculator.
Should Asian adults use different BMI cut-offs?
Some health bodies, including the NHS, suggest lower cut-offs for people of South Asian, Chinese and some other backgrounds, because health risks start at a lower BMI.