BMI Calculator
For adults aged 20 and over.
Calculate your BMI
Adult BMI categories (WHO / CDC)
Underweight< 18.5
Healthy weight18.5 to under 25
Overweight25 to under 30
Obesity30 or more
What BMI is
Body Mass Index (BMI) is your weight divided by your height squared (kg/m²). It is a quick screening number used by the WHO and CDC. It does not measure body fat directly and does not diagnose anything on its own.
What BMI cannot tell you
- Muscle vs fat: very muscular people can have a "high" BMI without much body fat.
- Where fat is: fat around the waist carries more health risk than the same BMI suggests.
- Asian populations: a WHO expert group found that health risks rise at lower BMIs in many Asian populations, and suggested extra action points (23 and 27.5).
- Children and teens: adult categories do not apply. Use BMI-for-age percentiles instead (see the CDC link below).
- Pregnancy: BMI categories do not apply during pregnancy.
BMI is one piece of information. Talk to a doctor about what it means for you.
Sources
- World Health Organization – Obesity and overweight fact sheet
- CDC – Adult BMI categories
- WHO Expert Consultation. Appropriate body-mass index for Asian populations. Lancet. 2004
- CDC – BMI for children and teens
Last reviewed 2026-09-26.