BMI Calculator
Enter your height and weight to get your Body Mass Index and weight category.
How BMI categories are defined
Under 18.5 is underweight, 18.5–24.9 is normal weight, 25–29.9 is overweight, and 30 or above is obese, per the standard WHO classification. BMI doesn't distinguish muscle from fat, so it's a rough screening measure rather than a diagnosis — athletes and very muscular people often read "overweight" despite low body fat.
About the BMI Calculator
Body Mass Index (BMI) is a quick screening number that relates weight to height. This calculator accepts metric (kilograms and centimetres) or imperial (pounds, feet and inches) units and shows your BMI together with the standard category: underweight, healthy range, overweight or obesity.
BMI is weight in kilograms divided by height in metres squared. The World Health Organization categories for adults are below 18.5 underweight, 18.5 to 24.9 healthy, 25 to 29.9 overweight, and 30 or higher obesity. Some health authorities in Asia use lower cut-offs because health risks can rise at lower BMI in some populations. BMI does not measure body fat, muscle, bone density or where fat is stored, so athletes and older adults can be misclassified.
How to use it
- Pick metric or imperial units.
- Enter your height and weight.
- Read your BMI and category.
- Use the result as a starting point for a conversation with a health professional, not as a diagnosis.
Tips and good to know
- Measure height without shoes and weight at a consistent time of day.
- BMI categories for children and teenagers use age- and sex-specific charts, so this adult tool is not suitable for them.
- Waist circumference and body fat percentage give extra context.
Frequently asked questions
Is BMI accurate?
It is a population-level screening tool and a rough guide for individuals.
What BMI is healthy?
For most adults 18.5 to 24.9 is the standard healthy range, but individual health depends on many factors.
Is pregnancy different?
Yes. BMI is not used the same way during pregnancy; ask your doctor.