BMI calculator (body mass index)
Body mass index in metric or imperial units.
Processed on your deviceHow to calculate BMI
- 1
Choose metric or imperial units.
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Enter your height and weight.
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Read your BMI and the WHO category it falls in, and talk to a health professional about what it means for you.
Frequently asked questions
How is BMI calculated?
Weight in kilograms divided by height in metres squared. For example, 65 kg ÷ (1.70 m × 1.70 m) = 22.5.
What are the BMI categories?
For adults, the WHO uses: below 18.5 underweight, 18.5–24.9 healthy weight, 25–29.9 overweight, and 30 or above obesity. Some health services use different cut-offs for some ethnic groups.
What doesn't BMI tell me?
BMI doesn't measure body fat, muscle, bone density or where fat is stored, so it can be misleading for athletes, older adults and during pregnancy. It isn't designed for children and teens, who are assessed with growth charts.