About the BMI Calculator

Body Mass Index, or BMI, compares your weight with your height to give a single number that is widely used to screen for weight categories in adults. This calculator works in kilograms and centimetres or in pounds, feet and inches.

Besides your BMI and its category, the tool shows the range of weights that would fall in the normal band for your height, which gives you a more useful target than the number alone.

How to use the BMI Calculator

Choose metric or imperial units.
Enter your height and your weight.
Press Calculate BMI.
Read your BMI, your category and the healthy weight range for your height.

How it works

BMI is your weight in kilograms divided by your height in metres squared. The World Health Organization groups adult BMI as underweight below 18.5, normal from 18.5 to 24.9, overweight from 25 to 29.9, and obese at 30 or above.

BMI is only a screening tool. It does not measure body fat, and it does not tell muscle from fat, so it can mislead for athletes, older adults and people with unusual builds.

Frequently asked questions

Is BMI accurate for athletes and bodybuilders?

Not always. Muscle weighs more than fat, so a very muscular person can have a high BMI without carrying excess fat. Waist measurement and body composition tests give a fuller picture.

Can children use this calculator?

No. For people under 20, BMI is compared with growth charts for their age and sex, which this tool does not do. Please ask a doctor.

What should I do if my BMI is outside the normal range?

A BMI outside the normal range is not a diagnosis. Speak to a doctor or dietitian, who can look at your overall health, diet and lifestyle.