Free tool
BMI calculator
Work out your body mass index, the healthy weight range for your height, and what those numbers actually mean. No sign-up, and nothing you type is stored against your name.
What the ranges mean
| BMI | Category |
|---|---|
| Under 16.0 | Severely underweight |
| 16.0 – 18.4 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity class I |
| 35.0 – 39.9 | Obesity class II |
| 40.0 and above | Obesity class III |
Adult cut-offs published by the World Health Organization. Calorie estimates use the Mifflin-St Jeor equation, and the waist thresholds are the WHO 2008 values.
Where BMI falls short
- It cannot tell muscle from fat. A rugby player and someone carrying extra weight can share a BMI and be in completely different health.
- It says nothing about where fat sits. Weight around the middle raises metabolic risk more than the same weight elsewhere, which is why the waist measurement above matters as much as the BMI.
- It does not apply to children. Under 18, growth is read against age and sex on a growth chart.
- It does not apply in pregnancy. Gaining weight is the point.
- It is a screening number, not a diagnosis. It cannot see your blood sugar, your blood pressure or what you eat.