How to use BMI Calculator
- Choose metric (cm and kg) or US units (feet, inches and pounds).
- Enter your height and weight.
- Read your BMI, category and healthy weight range. Tick Use Asian cut-offs if they apply to you.
About this tool
Body Mass Index is your weight in kilograms divided by your height in metres squared. For example, 68 kg at 1.70 m gives 68 ÷ (1.70 × 1.70) = 23.5.
For adults the World Health Organization uses these bands: under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, and 30 or more obese.
Health risks start at a lower BMI for people of South Asian, Chinese and other Asian descent. That is why the WHO and many health services suggest lower cut-offs for them: 23 for overweight and 27.5 for obese. Tick Use Asian cut-offs to use these.
BMI is a quick screening number, not a diagnosis. It cannot tell muscle from fat, so very muscular people can score high, and it is not used for children or pregnant women. Waist size and a doctor's advice give a fuller picture.
Questions and answers
What is a healthy BMI?
For most adults, 18.5 to 24.9. With Asian cut-offs, 18.5 to 22.9.
Is BMI accurate for athletes?
Not always. Muscle is heavy, so muscular people can have a high BMI while carrying little fat.
Can I use this for children?
No. Children and teenagers need age- and sex-specific BMI charts. Ask a doctor or use a growth chart.
What is BMI Prime?
Your BMI divided by the top of the healthy range. A value of 1.00 or below is within or below the healthy range.