BMI Calculator
Check your body mass index (BMI) from your height and weight. Use metric (cm, kg) or imperial (ft, in, lb) units and see your BMI, its category and the weight range that counts as healthy for your height.
- Metric and imperial
- Healthy weight range
- Adult categories
- No sign-up
BMI is a general screening number for adults. It does not measure body fat or muscle and is not a diagnosis. Talk to a doctor about your health.
How to use
- Choose metric or imperial units.
- Enter your height and your weight.
- Read your BMI and its category (underweight, healthy, overweight or obesity).
- Look at the healthy weight range for your height as a general guide.
What is BMI?
Body mass index is weight in kilograms divided by height in metres squared. The World Health Organization categories for adults are: under 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight and 30 or more obesity. The same limits apply to men and women.
Limits of BMI
BMI cannot tell fat from muscle, so very muscular people can score as overweight. It is also not designed for children, pregnancy or older adults in the same way. Use it as a screening number only. For other quick maths see the percentage calculator.
Frequently asked questions
How is BMI calculated?
BMI = weight (kg) ÷ height (m) squared. In pounds and inches the formula is 703 × weight ÷ height squared.
What is a healthy BMI?
For adults, a BMI from 18.5 to 24.9 is classed as a healthy weight by the World Health Organization.
Is BMI accurate for athletes?
Not always. Muscle weighs more than fat, so athletes can have a high BMI with a low body fat level.
Is my data saved?
No. The calculation happens in your browser and nothing is sent or stored.