Calculators
BMI Calculator
Calculate body mass index in metric or imperial units, with category and healthy weight range.
Body measurements
Results
BMI
23.5
Category
Normal weight
Healthy weight range
53.5 – 72 kg
WHO adult categories: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obesity. BMI is a screening number, not a diagnosis.
About this tool
Body mass index is a height-and-weight screening number. It is widely used, but it does not measure body fat, muscle or health on its own.
How to use
- Choose metric or imperial units.
- Enter height and weight.
- Read BMI, the WHO adult category and the healthy weight range for that height.
Formula and methodology
BMI = weight (kg) ÷ height (m)². Imperial inputs are converted first: 1 inch = 0.0254 m and 1 lb = 0.45359237 kg. Categories follow WHO adult cut-offs. The healthy range is the weight that produces BMI 18.5 to 24.9 at the entered height.
Worked example
A person who is 170 cm and 68 kg has BMI 23.5, in the normal-weight range. The healthy weight band for that height is about 53.5–72.0 kg.
Frequently asked questions
Is BMI accurate for athletes?+
BMI can overestimate risk for people with high muscle mass and underestimate it for some others. Treat it as a screening figure, not a diagnosis.
Does this apply to children?+
No. Child and teen BMI uses age- and sex-specific percentiles, which this adult calculator does not apply.
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