BMI Calculator
About BMI Calculator
Enter height and weight to get BMI and where it falls. The formula is kilograms divided by metres squared, so 72 kg at 1.70 m gives 24.9.
The bands here are the WHO ones: under 18.5 underweight, 18.5 to 24.9 normal, 25 to 29.9 overweight, 30 and above obese. China's standard sets the thresholds lower, at 24 and 28, which is why the same number can read "normal" on one site and "overweight" on another. Neither is wrong; they are different reference populations.
What BMI is genuinely good at
Comparing groups, and giving one person a rough starting point. It costs two numbers and correlates with body fat well enough at scale, which is why public health uses it.
What it cannot do
Tell muscle from fat. A 100 kg athlete and a 100 kg sedentary adult get the same number. It also says nothing about where the fat sits, and visceral fat is the part linked to metabolic risk.
For an individual, waist circumference and a body fat estimate say more. BMI is a screening number, not a diagnosis, and this page is not medical advice.
Frequently asked questions
Why is my BMI 'overweight' here but 'normal' elsewhere?
Different cut-offs. WHO puts overweight at 25, China's standard at 24 (and obesity at 28). This page uses the WHO numbers.
Does BMI work for athletes?
Poorly. Muscle is denser than fat, so muscular people often land in the overweight band with low body fat. Waist measurement or a body fat estimate is more useful there.
Should I aim for the middle of the normal range?
Not necessarily. The range is broad on purpose, and 22 is not automatically healthier than 24. A trend over months says more than one reading.
Is this medical advice?
No. It is arithmetic plus a reference table. Anything involving a diagnosis or a plan belongs with a doctor.
