Where does that BMI sit?
BMI is a population statistic used on individuals, which is why it works badly for anyone unusual. It is still the standard first look.
Healthy range
24 kg/m² — closest reference: overweight threshold at 25 kg/m².
Reference figures are measurements and are rounded; the unit conversion behind them is exact.
| Reference | Size | Yours ÷ theirs | Note |
|---|---|---|---|
| underweight threshold | 18.5 kg/m² | 1.3× | |
| healthy midpoint | 21.7 kg/m² | 1.11× | |
| overweight threshold | 25 kg/m² | 0.96× | |
| obesity threshold | 30 kg/m² | 0.8× | |
| severe obesity | 40 kg/m² | 0.6× |
Worth knowing
- BMI was devised in the 1830s by Adolphe Quetelet as a way of describing populations. He explicitly said it should not be used to judge individuals.
- Because it uses height squared rather than cubed, BMI systematically overstates the size of tall people and understates short ones.
Frequently asked
What is a healthy BMI?
18.5 to 24.9 by the WHO categories. The cut-offs differ for South and East Asian populations, where risk rises at lower values.
Why is BMI criticised?
It cannot distinguish muscle from fat, ignores where fat is carried, and scales wrongly with height. Waist-to-height ratio predicts metabolic risk better and is just as easy to measure.
How to read this
BMI is a screening statistic, not a diagnosis, and this page is not medical advice.