Home / Numbers / BMI Calculator
BMI Calculator
Work out body mass index from height and weight, in metric or imperial units.
What BMI tells you: body mass index is weight in kilograms divided by height in metres squared. It’s a quick screening number, not a diagnosis — it doesn’t distinguish muscle from fat, and the adult categories don’t apply to children, teens or pregnancy. Talk to a doctor about what a healthy weight means for you.
What are the BMI categories?
For adults (WHO): under 18.5 is underweight, 18.5–24.9 healthy weight, 25–29.9 overweight, and 30 or more obese.
About the BMI Calculator
The BMI Calculator works out your body mass index from your height and weight in metric or imperial units and shows which standard adult category you fall into. BMI is a quick screening number used by doctors and health services. It is a useful starting point for thinking about your weight, though it doesn’t account for muscle, age or body shape.
How to use the BMI Calculator
- Choose metric or imperial units.
- Enter your height and weight.
- Read your BMI and the category it falls in.
- See where you sit on the colour scale from underweight to obese.