Formula and interpretation
BMI is calculated by dividing weight in kilograms by height in metres squared. Adult BMI categories are commonly interpreted as underweight, healthy weight, overweight and obesity ranges.
Assumptions and limitations
This calculator is for adults. BMI does not directly measure body fat, muscle mass, fat distribution or individual health. Children, teenagers, pregnancy and some athletes need different interpretation.
References
- World Health Organization: Obesity and overweight, accessed 2026-05-13.
- NHS BMI calculator, accessed 2026-05-13.
- CDC adult BMI categories, accessed 2026-05-13.
FAQ
Is BMI a diagnosis?
No. BMI is a screening estimate and should not be used alone to diagnose health.
Why can BMI be misleading?
It does not distinguish fat from muscle and does not account for all differences in age, sex, ethnicity or body composition.
Last reviewed: 2026-05-13