Tools / BMI Calculator
BMI Calculator
Enter your weight and height to see your body mass index and the general range it falls in.
BMI is a screening number, not a diagnosis. Talk to a doctor about your health.
How BMI is calculated
Body mass index equals weight in kilograms divided by height in metres squared. In imperial units it is 703 × weight in pounds divided by height in inches squared. The World Health Organization groups adult results as under 18.5 (underweight), 18.5 to 24.9 (healthy range), 25 to 29.9 (overweight range) and 30 or above (obesity range).
What BMI does not tell you
BMI cannot tell fat from muscle, so very muscular people can score in the overweight range while having low body fat. It also ignores where fat is stored, age, sex and ethnicity. Some research suggests health risks begin at lower BMI values in South Asian populations, which is why doctors look at waist size, blood pressure, blood sugar and family history alongside BMI.
Using the result sensibly
Use BMI as a starting point for a conversation with a healthcare professional, not as a goal on its own. This calculator is for adults and is not suitable for children, teenagers or pregnant women.
Frequently asked questions
Is BMI accurate for athletes?
Not always. Muscle weighs more than fat, so athletes can show a high BMI despite being healthy.
Is the data saved?
No. Calculations stay in your browser.
Can children use this?
No. Children's BMI is compared against age and sex percentiles, which this tool does not use.